Speed cooking oven

ABSTRACT

A speed cooking oven is disclosed comprising a cooking cavity, a controller, thermal heating source, blower assembly, air directing means and a vent assembly. Hot air is circulated by the blower motor assembly into the oven cavity where the hot air is directed in a maimer wherein a conflicting, colliding turbulent gas flow is directed at a food product providing for the rapid cooking of food products.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 10/614,479, filed Jul. 7, 2003, entitled “SPEED COOKING OVEN,”to issue on Apr. 5, 2005 under U.S. Pat. No. 6,874,495, which claims thebenefit of U.S. Provisional Application No. 60/394,216, filed Jul 5,2002, entitled “RAPID COOKING OVEN.”.

The present application is related to U.S. Provisional Application No.60/550,578, filed Mar. 5, 2004, entitled “SPEED COOKING CONVEYOR OVEN;related to U.S. Provisional Application No. 60/513,110, filed Oct. 21,2003, entitled “SLOTTED ANTENNA;” related to U.S. ProvisionalApplication No. 60/513,111, filed Oct. 23, 2003, entitled “MICROWAVEANTENNA COVER FOR RAPID COOKING OVEN;” related to U.S. ProvisionalApplication No. 60/614,877, filed Sep. 30, 2004, entitled “SLOTANTENNA;” and related to U.S. Provisional Application No. 60/615,888,filed Oct. 5, 2004, entitled “CATALYST FOR SPEED COOKING OVEN.”

In addition, the present application is related to co-pending U.S.patent application Ser. No. 10/614,268, filed Jul. 7, 2003, entitled“MULTI RACK SPEED COOKING OVEN,” which claims the benefit of U.S.Provisional Application No. 60/394,216, entitled “RAPID COOKING OVEN,”filed Jul. 5, 2002; related to U.S. patent application Ser. No.10/614,710, filed Jul. 7, 2003, entitled “SPEED COOKING OVEN WITH GASFLOW CONTROL,” which claims the benefit of U.S. Provisional ApplicationNo. 60/394,216, entitled “RAPID COOKING OVEN,” filed Jul. 5, 2002;related to U.S. application Ser. No. 10/614,532, filed Jul. 7, 2003,entitled “SPEED COOKING OVEN,” which claims the benefit of U.S.Provisional Application No. 60/394,216, entitled “RAPID COOKING OVEN,”filed Jul. 5, 2002; and to related co-pending International ApplicationNo. PCT/US2005/007261, filed Mar. 7, 2005, entitled “CONVEYOR OVEN,”which claims the benefit of U.S. Provisional Application No. 60/550,578,filed Mar. 5, 2004, entitled “SPEED COOKING CONVEYOR OVEN,” the benefitof U.S. Provisional Application Ser. No. 60/551,268, filed Mar. 8, 2004,entitled “ANTENNA COVER,” and the benefit of U.S. ProvisionalApplication No. 60/615,888, filed Oct. 5, 2004, entitled “CATALYST FORSPEED COOKING OVEN.”

The present application contains technical disclosure in common withco-pending International Application No. PCT/US/2003/021225, entitled“SPEED COOKING OVEN,” filed Jul. 5, 2003, which claims the benefit ofU.S. Provisional Application No. 60/394,216, filed Jul. 5, 2002,entitled “RAPID COOKING OVEN;” and contains technical disclosure incommon with International Application No. PCT/US/2004/035252, filed Oct.21, 2004, entitled “SPEED COOKING OVEN WITH SLOTTED MICROWAVE ANTENNA,”which claims the benefit of U.S. Provisional Application No. 60/513,110,filed Oct. 21, 2003, entitled “SLOTTED ANTENNA,” which also claims thebenefit of U.S. Provisional Application No. 60/513,111, filed Oct. 23,2003, entitled “MICROWAVE ANTENNA COVER FOR RAPID COOKING OVEN,” whichalso claims the benefit of U.S. Provisional Application No. 60/614,877,filed Sep. 30, 2004, entitled “SLOT ANTENNA.”

Each of these applications are incorporated herein by reference as iffully set forth herein.

BACKGROUND

This invention pertains to the art of cooking appliances and, moreparticularly, to an oven for cooking a food product by air alone; or acombination of air and microwave energy. The invention has particularapplication to high speed cooking of food products at very high qualitystandards.

Restaurants and commercial cooking establishments have a need for fastercooked food in order to more efficiently run and maintain theircommercial businesses. The ability to more rapidly cook food, andthereby more quickly serve food and move customers through a restauranthas great value during peak times when table space may limited due tohigh customer traffic. Therefore, speed cooking ovens are becoming morewidely known and utilized by those skilled in the art of commercialcooking. There exist several types of commercial speed cooking ovens onthe market today. These commercial cooking ovens utilize varioustechniques to accomplish speed cooking and have been and are referred toherein as “hybrid” ovens, and are generally defined as ovens that employa combination of microwave energy and at least one other thermal source(convection, radiant energy, and/or steam) to increase cooking speedover a conventional oven, while at the same time maintaining a qualityof cooking reasonably similar to a conventional cooking oven. As usedherein the terms “hybrid” and “combination” have the same meaning unlessotherwise specified and the terms “conventional cooking oven”“conventional cooking” and “conventional means”, have the same meaningand refer to cooking at the quality level and at the speed that iscurrently widely utilized. By way of example, the “conventional cookingtime” for a brand name of Grand Cinnamon rolls, according to thepackage, is approximately 28-30 minutes (e.g. conventional cookingtime).

Just as speed cooking will become the standard for commercial cooking,speed cooking also has application in residential cooking, and willbecome the standard for residential use also. The ability to quicklycook food, and the ability to cook a variety of food products togetherwithout flavor or odor transfer from one food product to the next,within the same cooking operation, is desirable and of high interest toresidential as well as commercial users.

There have been relatively few dramatic changes in the cooking art overthe years, as man has moved from open flame cooking at the campfire togas fired and electric resistance heating elements for cooking; andlater the introduction of the microwave oven totally revolutionized thefood industry as new food products were developed, new methods of fooddistribution developed and new and different opportunities opened up forresidential and commercial establishments as re-thermalization of foodproducts, very quickly, became possible. It is not necessary to recountthe dynanic impact the introduction of the microwave has had on dailylife, and also the many industries that were created because of theintroduction of affordable microwave re-heating devices.

High quality speed cooking will become the next standard as people willwant the ability to cook very quickly, but also will want a high qualityfood product. It is always therefore very important that speed cookingproduces a finished food product that is at least as good asconventionally cooked food products, and in some cases as high asgourmet standards. For example, a frozen pizza can be cooked in just 3minutes or less in a speed cooking oven as compared to the conventionalcooking time of approximately 25-30 minutes in a conventional oven. Or,cinnamon rolls cooked from raw dough can be cooked in a speed cookingoven in 2-3 minutes instead of the conventional 28-30 minutes. Each foodproduct can be cooked at these speeds and maintain the taste appearanceand overall quality of a conventionally cooked food product. Animportant aspect of proper speed cooking is that the food productproduced in a speed cook oven (in 1/7^(th) to 1/10^(th) the time in aconventional oven) is at or above the taste, appearance, quality andperformance levels of the same food product cooked by conventionalmeans. As this new and exciting technology is introduced into the marketand becomes commercially and residentially available, the entire foodindustry will be re-energized and re-organized around new and differentmethods of food production, packaging, transportation, delivery,preparation and cooking of food products.

One reason the average family takes less time today to be together formeals is because the time required to prepare a complete meal, includingthe cooking time, is more time than most people are willing to invest.With quality speed cooking, cooking will become “just in time” or “ondemand” as people will be able to cook foods 5 to 10 times faster thanconventional cooking, and at quality levels equal to or higher thanconventional cooking. The ability to custom cook, on demand, willrevolutionize cooking, and food preparation. With this invention it ispossible to short order cook exactly the food each person desires.Instead of “meatloaf tonight” it will be possible for one person to havesteak, another chicken and another pork chops, because these food itemscan be cooked, from raw, together, in this speed cooking oven in afraction of the time of conventional cooking. Or, for example picture anafternoon dinner party where fresh fish is laid out on a bed of ice. Asguests approach the fresh fish selection, each can pick out a particularfilet and watch as each filet is cooked perfectly in just a minute ortwo. Additionally, the person cooking the food will have the ability tocontrol how well done the fish is cooked, the degree of browning on theoutside (both top and bottom) and the inside temperature of the fish. Ifone person desires a salmon filet lightly done, this may take 1 minutewhile the next person may desire a well done filet which may, forexample, only take an additional 20 seconds.

In addition to the speed advantage, this invention produces very highquality food products that are cooked perfectly—cooked the way the foodproduct should be cooked instead of cooking using the conventionalmethod. Historically, conventional cooking ovens heat to a predeterminedtemperature before the food product is inserted into the oven. Once thefood product is inserted into the oven and over a period of time, theheat that has built up within the oven to a pre-heat temperature slowlyconducts through the entire food product until there is overall heatingof the interior of the food. This process is inefficient, but peoplehave nevertheless developed the skill level necessary to overcome theinefficiencies of the method. With this invention food is cookedperfectly with less waste from boil off, cook off or other loss of foodproduct due to the cooking process. As such, it will be possible todevelop food products with fewer or less initial ingredients and stillobtain the same final finished cooked food product. This inventiontherefore also relates to methods of food production wherein feweringredients are needed in order to attain the same final cooked product.Cooking with this new and novel method will allow food companies toreduce the quantity of the initial ingredients utilized for foodpreparation, but still maintain the final end product after the cookingprocess. Because this cooking process requires less initial startingingredients (weight and volume) less packaging material is thereforerequired. Smaller package size leads to more space on the groceryshelves and in refrigeration coolers. Shipping costs, packaging costs,shelf space in grocery stores and many other areas of the foodproduction system and delivery chain will be impacted as the world offood preparation, storage, transportation, delivery, preparation andsale moves from conventional cooking to speed cooking. In addition tothe previously mentioned benefits, the ability to cook to gourmetstandards with this invention will spawn an entire industry whereingourmet signature chefs will be able to develop, brand and market theirsignature products for people to take home and enjoy without the cost ortime expense of dining at a Five Star Restaurant. The speed cooking ovendescribed herein will also be capable of internet connectivity.Information such as recipes, cook settings, special cooking instructionsfor gourmet food products can all be downloaded from the internet andimported directly into the cooking oven. Additionally, diagnostic toolswill enable service providers to better predict future componentbreakdowns and also predict regular maintenance requirements, as remotemonitoring of the oven will be possible.

Today there are a number of combination ovens sold for commercial usethat cook in the range of two to three times faster than conventional.These ovens typically have an oven cavity roof or back wall launch ofthe microwave energy into the cooking cavity, with a simple convectionflow of air that creates a gentle air flow pattern within the oven.

Fast cooking ovens in the 2 to 3 times speed range have also beendeveloped.

Compared to the higher speed hot air impingement flow speed cookingovens, the more traditional microwave convection oven is a relativelysimple rapid cook oven capable of cooking speeds of up to 3 times fasterthan conventional. These ovens utilize a convection blower motor andblower wheel mounted on the back wall (or side wall) with the oven airbeing drawn directly into the inlet and discharged from the blower wheelperimeter. A baffle plate isolates the blower discharge from the inletand creates an outward flow of air along the oven cavity side, roof andfloor walls, with the air flow turning back over the food and returningto the blower inlet. The baffle plate looks like a false back wall withgaps around the edges for air discharge and an opening in the center forair return and microwave energy in these ovens has been introduced fromtop, bottom, or the side walls. In general, these designs have a numberof limitations and drawbacks. The first limitation is that the microwavelaunch system cannot equally illuminate multiple racks or pans of food.As a result, the efficiency of the microwave energy must be purposelyreduced in order to avoid hot spots and poor cooking quality. Second, ina top (roof) launch or bottom (floor) launch microwave system, thecooking pans or other cooking vessels containing the food are situateddirectly above (in a bottom launch system) or directly below (in a toplaunch system) the microwave launch system which obscures the microwaveenergy from the pans further away from the microwave illuminationsource. To compensate for the non-uniform illumination of the microwaveswithin the oven cavity, the design of the oven microwave system ispurposely limited in order to achieve uniformity. As a result, mosttraditional microwave convection ovens are actually single rack positionrapid cook ovens. Many of these top or bottom launch systems requireeither a mode stirrer (a mechanical device to stir the microwave “efield”) or a turntable that rotates a platter or plate upon which thefood rests (top launch system), or in some cases both a mode stirrer anda rotating tray is utilized. In addition to the microwave energy fieldnon-uniformity, the convection air flow also has non-uniform behaviorwhich results in lower air flow rates in the oven limiting theconvection heat transfer rate, thereby limiting the cooking speed of theoven.

Generally, these oven designs direct the oven air flow down the sidewalls until the air flow reaches the oven cavity floor, then the airturns towards the back wall, flowing over the food product beforereturning back to the blower inlet and all the air returns to the blowerinlet opening (usually located in the center of the back or side wall).The center pan often has a distinctive “V” cooking pattern near theblower inlet and this creates flow non-uniformity from the center rackposition to the top/bottom positions. Balancing the air flow overseveral pans or cooking vessels is difficult as the air is drawn to thecenter of the back wall. As discussed herein, imparting high air flowsto the oven in order to achieve high cook speeds results in non-uniformcooking. Usually, the discharge from a baffle plate is adjusted with airflow vanes or flow restrictions in order to achieve a more uniform flowstate. The effectiveness of this approach is limited, and in general theoven air flow rates are maintained at modest rates.

In addition to the drawbacks described above relative to cooking speeds,these oven designs do not manage or handle air borne grease entrained bythe convection air and by health code, these ovens must be operatedunder a hood when cooking meats or other grease laden foods. Informationrelevant to attempts to address these problems can be found in U.S. Pat.Nos. 4,337,384; 4,431,889; 5,166,487 and EP 0429822AJ. They have somespeed advantage, but are not fast enough to radically change the cookingoperation in a restaurant, commercial establishment or the home kitchen.

It has been found that, in order to create a break-through in thecurrent cooking environment, cooking speeds greater than 5 timesconventional cooking speeds must be achieved. A number of developmentshave taken place to create high speed commercial cooking ovens in the3-10 times faster than conventional range, but fundamental drawbacksexist in these high speed commercial ovens and approaches. These ovenscook at high speed but some do not provide a quality finished foodproduct. These ovens tend to be complex, unreliable and expensive tomanufacture. As such, the finished sales price is high, thereby limitingthe demand for, and commercial success of the ovens. Due to the state ofthe art of these high speed commercial cooking machines, the ovencavities tend to be small, they create smoke and odor, and thereforerequire expensive ventilation or catalytic clean-up. They are generallydifficult to maintain, generally employ the use of a complex userinterface with multiple control variables, and generally require largepower supplies. They also tend to be less reliable due to the use ofspecialized components.

There have been different approaches to high speed cooking utilized inthe past. One is impingement style air flow coupled with microwave, andanother is convection style gas flow with microwave. Several high speedcooking ovens featuring impingement style convection flow fields coupledwith microwave energy have been developed and impingement style heattransfer is not new in the art. As an example, impingement style heattransfer has been described in the General Electric Heat Transfer DataBook 1981 as “One method of producing relatively large forced convectionheat transfer coefficients on a surface by gas (or other gases) is theuse of a multiplicity of jets impinging upon the surface. As the gas jetapproaches close to the surface it turns by an angle of 90 degrees, andthereby becomes what is called a “wall jet” FIG. 1 (after the 90 degreeturn). This type of impinging heat transfer has been studied extensivelywith predictive heat transfer relationships and the use of thisimpingement style cooking has historically been employed.

Some of the current oven designs feature opposed primary energy flowswith impingement convection heat transfer being directed onto the uppersurface of the food product (straight down at 90 degrees to the foodproduct) and microwave energy launched from the floor of the oven cavityinto the bottom of the food product. To provide bottom side convectionheat transfer, the impingement air flow is pulled around the sides ofthe food product and across the bottom of the food via a low pressuregas return duct located directly below the food and has been describedas a “shroud effect”. The flow beneath the food is accomplished using aceramic platter with stand offs that have the dual purpose of supportingthe food product and directing air flow along the bottom side of thefood (as the standoffs are used to elevate the food thereby creating theair flow passage ways) with the air flow exiting downward via a seriesof apertures in the ceramic platter. The microwave energy is launchedfrom below the food product and enters the food after passing throughthe ceramic platter, such ceramic platter is microwave transparent toallow the passage of the microwave energy through the platter and intothe food product. While this approach produces high cooking speeds (5-10times faster than conventional oven) it has several limitations as theovens have non-uniform energy fluxes (convection and microwave) betweenthe top and bottom of the food product thereby requiring complex controlof the microwave and convection heating systems (sub-systems) to achievespeed cooking. In general, both the microwave energy and the convectionenergy flows are adjusted several times during the cooking cycle. Thedevices used to accomplish this adjustment are intensive blower motorsand blower motor speed controllers, microwave power modulation, and acomplex oven controller/user interface (needed to input multiple powerand time settings for a given recipe). These devices are expensive anddramatically add to the complexity and cost of the final product.Additionally, these sub-systems tend to be unreliable, causing highservice callouts. To achieve high speed the ovens require a relativelycomplex and expensive variable speed convection blower motor speedcontrol with dynamically braking blower motor speed controllers andsophisticated electronic oven controls. The air blower must havevariable speed capability in order to provide lower convective heattransfer rates when cooking more delicate food products such as cakesand other pastries. These ovens also have a lack of independent top sideand bottom side convection (browning) heating because top impingementflow must wrap around the food product and flow under the food productin order to accomplish bottom side heating/browning. This requires theuse of the previously mentioned expensive, fragile, and difficult toclean microwave transparent ceramic platter, which allows for thepassage of microwaves. The ceramic platter must be configured with airflow channels in order to accomplish bottom side browning. The ceramicplatter is expensive to manufacture, chips easily (creating health,performance and reliability problems) and requires regular cleaning,maintenance, and replacement. Because the ceramic platter is a necessarycomponent, if a spare is not kept on hand, the oven is renderedinoperable in the event a platter is broken. Supply chains, stocks ofinventory and additional money must be set aside in order to assure aconstant supply of these ceramic platters. Indeed, ovens utilizing theseceramic platters have met with difficulty when introduced intocommercial establishments with the prospective owners of these ovensconstantly battling reliability problems and the need to re-supply theircommercial establishments with ceramic platters. As an example of oneproblem, a chipped ceramic platter absorbs moisture, grease, oils andother by-products of the cooking process. As water, for example isabsorbed within these platters, microwave performance decreases becausethe microwave energy interacts or couples with the water molecules (theprinciple of a microwave oven is the excitation of the oxygen-hydrogenbond within the water molecule) thereby reducing the microwave energyavailable for cooking. At some point, the overall oven heat willeventually, at least somewhat, dry a water soaked ceramic platter byboiling off the trapped water within the platter, but until this occurs,varying degrees of cooking performance may be experienced due to thevarying moisture content within the platter. As more water is evaporatedfrom the platter, more microwave energy is then available to couple withthe food product instead of the water trapped within the platter. A foodproduct cooked upon a water soaked platter will take longer to cook (orat least that portion of the cooking attributable to microwave energy)than the same food product cooked upon a dry platter. For this reason, aspeed cooking oven requiring the use of a ceramic platter with aperturesto both direct air flow and exhaust air flow is undesirable, but isnevertheless necessary as the described oven utilizes the “shroud” or“wrap” effect in order to fully and somewhat properly cook the foodproduct; and the shroud effect is only created by the wrapping of theair around the food product via use of the ceramic platter. Also, withthe requirement of very rapid air circulation through the oven (highvelocity impingement), these ovens tend to be noisy. Cycling of theseovens from low velocity to high velocity generally produces a whirringnoise not dissimilar to the sound of a jet engine winding up.

In these ovens, a uniform vertical jet flow field, over a range of flowrates, is needed for cooking over the entire cooking rack area. A commonresult of this requirement is that there is a lack of uniformity; so itis necessary to restrict or reduce the cooking zone to that area thatexperiences appropriate cooking, relative to the platter. This reducesthe cooking capacity for a given oven cavity size because less of theplatter can be cooked upon.

Especially lacking in these ovens is the ability to cook in the cornersections of the oven. With other technologies, means to overcome thisproblem are complex and have at least partially been solved by rotationof the food product under air jets with the use of a turntable. Usingrotation (turntable) to compensate for jet non-uniformity also has theeffect of reducing the useful cooking area of the appliance by at leastapproximately 25%. The circular turntable within either a square orrectangular oven cavity bottom does not take advantage of the cookingarea located within the comers of the oven. In addition to thepreviously mentioned drawbacks of the ceramic platter, the platterfurther complicates the ability to achieve uniform flow conditionsbecause the vertical jet air flow pattern couples to the ceramic platterwhich is being used to channel flow under the food. Additionally, thenon-uniformity is a function of the shape and size of any cooking vesselused (e.g. pan, cookie sheet) because the air flow must wrap around thecooking vessel. In addition to the problems associated with these otheroven cavity bottoms, the design and construction of the oven cavity topis complex given the need to add or modify the oven cavity roof forimpingement nozzle plates/supply ducts. Also, modification of the ovencavity bottom is required for microwave launching, modification of thebottom and/or back wall is required for return gas ducts, andmodification of the oven cavity top is required for the impingementstyle gas nozzles. Taken together, these modifications result in a smallcook chamber section volume as compared to the entire oven cavityvolume.

Another disadvantage in the previously described oven is that it isdifficult to provide a microwave seal to the cavity floor (microwavelaunches through the oven floor through a circular waveguide) to preventgrease/liquid contamination of the wave guides. This is importantbecause grease, water vapor or other particulate contamination of themicrowave waveguide causes premature failure of the magnetron (tube)used to generate the microwave energy or “e-field” within the ovencavity. In these ovens, an opening in the oven cavity floor bottomallows the microwave launcher to extend up and through the oven cavityfloor but the launcher must be sealed with a material that allows thepassage of microwave energy, without any leakage of the seal becauseleakage of the seal then allows grease, food products and otherby-products of the cooking process to contaminate the microwavelaunching system, thereby reducing the life of the microwave system,causing again, as described above, tube failure and service callouts.

Another disadvantage of the high speed ovens described above is thatthey require grease control because of the high velocity of theimpinging air jets. This high velocity air impingement flow tends toentrain grease, both particles and vapor, into the convection gas, whichquickly soils the oven cavity surfaces. One method of dealing with thisgrease load has been the use of a large catalyst to control the airbornegrease. Drawbacks of the catalyst include its high cost and the catalysttends to cause a pressure drop in the impingement air flow, therebyreducing operating efficiencies. The pressure drop is compensated by theuse of a larger blower, thereby increasing component cost and loweringoperating efficiencies and raising energy costs. The catalysts must bereplaced periodically, adding both a service cost and an equipment costto the oven.

Other technologies use a different impingement approach where verticalair jets are generated from the oven roof and floor simultaneously. Theoven cavity bottom or floor impingement jets provide for bottom sidecooking/browning while the oven cavity roof jets provide top sidecooking and browning. In this device, the microwaves are launched fromabove the food product. Like the high velocity gas impingement air flowtechnology described above, this approach has several drawbacks.

First, the floor located gas nozzle plate and its supply duct are verydifficult to maintain given their susceptibility to food spoils, spillsand grease accumulation. To utilize the entire (or nearly) cooking area(rack), the top and bottom air jets must be very uniform in velocity ora non-uniform cooking and browning of the food product will result wherethe impingement jets produce circular brown spots on the food productsurface. This polka dot browning effect is, of course generally notacceptable. Additionally, the requirement for very uniform gas flow tothe food product adds complexity to the air flow system.

Second, uniform air jet fields are difficult to achieve at flows otherthan the design flow rates. When lower air flow rates (velocities) areneeded, such as with pastries, it is difficult to attain proper air flowrates less than the design flow rate specified for higher air flows.Such reduced flows will minimize the effective cooking area within theoven cavity to a portion of the cavity where a reasonable flow fieldexits in order to cook a food product to an acceptable quality level.Alternatively, to compensate for the requirement of a less aggressiveair flow, the convection flows must be greatly reduced, which willresult in longer cook times (defeating the desire for a speed cookingoven).

Third, the general oven construction is complex, as the supply duct tothe roof air plate must also act as a launch box for the microwaves.This requires that the roof jet plate be transparent to microwaves(e.g., ceramic plate with jet holes) so that the microwaves can belaunched through the plate. Additionally, the floor ducts may becomecomplex parts in the event they are designed to be removed for cleaningand/or servicing.

Fourth, having supply ducts on the floor and roof of the oven cavitygreatly reduces the useful volume (cook section) of the oven because asmuch as half of the height of the oven cavity is occupied by these airchannels. Other techniques have been used in an attempt to overcomethese issues, but these techniques generally require more complexitysuch as oscillating nozzles, rotating food support, special foodcontainers, and a smaller cook section and the work arounds tend to addcomplexity, cost and create other undesirable issues.

Finally, the previous approaches described for speed cooking ovens aresuited for single rack cooking or single level cooking. Impingementstyle air flow is ineffective with two or more rack positions becauseone rack with food product will block air flow to the second or thirdrack.

During normal conventional cooking, metal pans, metal pots and metalsheet pans (and other metal products) are generally used, bothcommercially and residentially and the use of metal pans is widespread.It will be difficult for speed cooking ovens to become popular withineither the commercial foodservice marketplace or within the residentialmarket unless quality speed cooking utilizing metal pans can beaccomplished.

Generally, speed cooking is slowed by the use of metal pans as microwaveenergy cannot penetrate and is deflected (re-distributed) within theoven cavity by the pans. Additionally, the metal pans completely blockmicrowave energy when the energy is directed from below the pan on asingle rack oven or in a top launch oven, the microwave energy isblocked from the lower pan by the top pan. It is therefore desirablethat a speed cooking oven is capable of speed cooking, at high qualitylevels utilizing metal pans.

Another problem generally encountered is that browning of the lowersurface of the food product is difficult to control because the methodgenerally utilized for bottom side browning is conduction through ametal pan (pan is heated by radiant or microwave energy and then thethermal is transferred to the food product by direct contact with thefood product) and this heating produces a griddle effect, therebybrowning the bottom side of the food product. This method is difficultto control and generally produces an over brown or burned bottom surfaceof the food product. The ability to properly brown the bottom side of afood product, within a metal pan, is therefore important.

Accordingly, it is an object of the present invention to provide amethod and apparatus for speed-cooking within a single-rack oven with animproved gas flow design capable of cooking most food products 5 to 10times faster than conventional cooking.

It is another object of the present invention to provide such a speedcooking oven which utilizes a gas flow pattern that averages out themaximum and the minimum gas flow variation for a given point in the ovencook section resulting in a gas flow that is averaged spatially over thefood product surface.

It is also an object to provide such a speed-cooking oven that producesuniform low flow conditions required for high quality baking.

A further object is to provide such a speed-cooking oven with acontinuous floor that is not interrupted by gas ducts or microwavelaunching and/or other systems and is easy for the user to clean andmaintain.

Another object is to provide a means to produce and direct various gasflow patterns in the oven that either reduce or enhance the convectionheat transfer coefficient to the product.

It is another object to provide a relatively constant flow through theoven which eliminates the need for varying the air flow therebyimproving grease extraction by maintaining higher flow rates through-outthe cooking cycle regardless of the required heat transfer to theproduct.

Another object is to provide such an oven with a simplified ovenconstruction, eliminating the need for variable speed impingement airblowers, dynamically braking blower motor speed controllers andassociated electronics.

Still another object is to provide a speed cooking oven that is capableof high quality speed cooking within metal pans, pots, sheet pans andother metal cooking devices found in residential and commercialkitchens.

Another object is to provide a speed cooking oven that is capable ofperforming bottom side browning of the food product utilizing gas flowto the bottom surface of the food product without the use of floormounted air plates.

Another object is to provide such a speed-cooking oven that increasesthe useful oven cook section height by eliminating ducts and/or jetplates from the floor of the oven.

Another object is to provide such an oven with a gas flow field wheregrease entrainment is reduced by eliminating the vertical impingementstyle flow that tends to throw or kick grease into the gas stream fromboth the cooking pan and the food product, while achieving sufficientlyhigh heat transfer rates.

Another object is to provide such an oven that matches the generalmicrowave and convection heat transfer energy patterns, such thatuniform cooking conditions can be achieved on the top side and bottomside of the food product.

Another object is to provide such an oven with gas deflection means thatallows flexibility of gas diversion throughout the speed cooking oven.

It is a further object to provide such an oven for speed cooking onmultiple racks.

It is a further object to provide such an oven which is more costeffective to manufacture and easier to clean and maintain.

Yet another object is to provide such an oven which is more reliable dueto improvements and simplifications in component sub-systems.

Other objectives, features and advantages will be apparent in thewritten description which follows.

SUMMARY

It has now been found that the above objects are obtained in a speedcooking oven provided with a unique combination of high gas flow ratesthat are averaged at the food product surface, and a means for changingthe convection heat transfer rate to the food product by controlling theoven gas flow patterns. Additionally, side wall mounted microwavesystems may be utilized. As used herein, the term “gas” includes, but isnot limited to air, nitrogen and other fluid mixtures that may beutilized within the cooking art. The exemplary embodiment of the speedcook oven has a simple construction featuring two small fixed blowersused to re-circulate hot gas within the oven cavity. Convection gas issupplied to the oven cook cavity by slotted or perforated cavity airdistribution plates that direct gas flow to the top, sides, and bottomof the food product. The gas flow angle to the product is greater thanapproximately zero degrees from horizontal (cavity floor as horizontalreference) and less than ninety degrees from the horizontal floorsurface. Gas flows from the top left side of the oven conflict andcollide with gas flows from the top right of the oven upon the surfaceof the food product. This turbulent mixing of the left and right gasflows at the surface of the food product produces a spatially averagedgas flow that effects rapid cooking of a food product. While top gasflows glance off of each other, conflicting, colliding and mixing uponthe top surface of the food product, gas flow is directed towards thebottom of the food product from the lower left and lower right portionsof the oven cavity. This gas also mixes at the bottom surface of thefood product, conflicting and colliding thereby causing a spatialaveraging of the gas flow at the food product surface, effecting rapidcooking of the food product. As used herein, the term “rapid cooking”and “speed cooking” have the same meaning and refer to cooking at ⅕^(th)to 1/10^(th) the time of conventional cooking. Once the gas hascirculated around the food product, it is drawn to the roof (top) of theoven cavity for convection heating, grease control, odor control andeventual movement to the inlet side of the convection blowers and returnto the oven cavity. The oven therefore utilizes a closed system whereinthe spent air is re-circulated through the oven many times during acooking operation.

A first conventional microwave waveguide with slotted antenna ispositioned along the left side wall, and a second conventional microwavewaveguide with slotted antenna is positioned along the right side wallof the oven cavity. The microwave feeds (antenna) are centered near thecooking rack level (below the upper gas supply duct), such that nearlyequal amounts of electromagnetic energy is directed towards the top andbottom surfaces of the food product. Standard 2.45 GHz microwaveproducing magnetrons (tubes) are used, producing a maximum power levelfor the oven of approximately 2000 watts (delivered to the food) orapproximately 1000 watts per microwave magnetron.

After the gas passes over the food product and through the cavity, itflows up to the oven roof where it exits the oven cavity. As the gasflow exits the oven cook cavity it passes over a thermal device (eitheran electric resistance, infrared, or natural gas fired convection gasheater, or other means of heating which may be direct or indirectheating). When electric heating elements are used, the preference is asheath type heater configured into a compact coil shape. Depending uponthe oven size and desired speed of cook (i.e., gas flow rate through theoven) the heater will deliver approximately 2500-4000 watts of energy tothe gas. The thermal delivery to the gas flow is variable depending uponthe particular characteristics of the particular speed cooking ovenapplication and the exemplary oven described operates at fromapproximately 2500-4000 watts. The oven cavity roof mount gas heaterlocation is ideal for a gas fired gas heater relative to ease ofinstallation, serviceability, and the ability to incinerate greaseparticles that come in contact with the very hot product of combustion.Of course, the hot products of combustion are mixed with the oven gasreturning to the blower. A number of gas combustor types are suitablefor this application including a surface type burner and a typicallyburner input rate would, for example, be in the 14,000 Btu/hr range, buta larger or smaller burner may be utilized.

To prevent excessive grease build-up in the oven, a means to removegrease for the convection gas is incorporated into the oven. Immediatelyafter the air passes over the gas or electric heater, but before the gasenters the blower inlet, it passes through a grease control device. Thisdevice mechanically separates the grease particles greater than 3.0microns from the gas flow. The roof location makes it ease to installand service such a device.

The gas flow is directed from the blowers and into ducts that delivergas from the left and the right sides of the oven cavity. The gas flowenters the oven cavity from the left side and from the right side and isdirected over the top and bottom surfaces of the food product in amanner wherein the gas flow from the left side conflicts, collides andturbulently mixes with the gas flow from the right side of the oven atthe top surface and at the bottom surface of the food product. Thisturbulent mixing of the gas flow patterns at the food product surfaceproduces high heat transfer, thereby producing rapid browning and rapidcooking of the food product.

Additional objects, features and advantages of the present inventionwill become readily apparent from the following detailed description ofthe exemplary embodiment thereof, when taken in conjunction with thedrawings wherein like reference numerals refer to corresponding parts inthe several views.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asa preferred mode of use, further objectives and advantages thereof, willbest be understood by reference to the following detailed description ofan illustrative embodiment when read in conjunction with theaccompanying drawings, wherein:

FIG. 1 is a cross sectional view of Impingement style heat transfer

FIG. 2 is a front elevation of a single rack oven according to thepresent invention

FIG. 3 is an isometric view of the left side and left front of oven

FIG. 4 is a top view of oven

FIG. 5 is a front view illustration of microwave electromagnetic fields

FIG. 6 a is a front view of aggressive gas flow

FIG. 6 b is a front view of less aggressive gas flow

FIG. 7 is an isometric view of the right side and right front of oven

FIG. 8 is a front elevation view of microwave energy distribution

FIG. 9 a is a side view of grease extractor

FIG. 9 b is a top view of grease extractor

FIG. 10 is a front view of left side oven wall illustrating microwaveantenna

FIG. 11 is a front elevation of single rack oven with gas flow control

FIG. 12 is a top view oven with gas flow control

FIG. 13 is a left side section detail of gas flow control

FIG. 14 a is a front view of oven gas flow control with aggressive gasflow

FIG. 14 b is a front view of oven gas flow control with less aggressivegas flow

FIG. 15 is a right side section detail of gas flow control

FIG. 16 is a front view of multi rack oven

FIG. 17 is a front view of right side of oven illustrating microwavesystem

FIG. 18 is a top view of multi rack oven

FIG. 19 a is a side view of grease extractor

FIG. 19 b is a top view of grease extractor

FIG. 20 is a front view of multi rack side section

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The speed cook oven of the exemplary embodiment is shown as a standalone commercial cooking appliance, but it is obvious to those skilledin the cooking art that this stand alone speed cooking appliance mayexist in many other commercial and residential embodiments (e.g.counter-top oven, wall-oven, single rack oven, multi-rack oven) becausethe speed cook oven is scalable up or scalable down. As used herein, theterm scalable has the meaning that additional larger or smallerembodiments can be developed for commercial and residentialapplications. Of course each embodiment or version may have differentsize characteristics, and require different voltages of electricity—ascommercial power supplies are generally different than residential powersupplies. This speed cook oven is therefore not limited to commercialuses only, and is equally applicable for residential (home) use. Withinitial reference to FIGS. 2-6, a speed cook appliance 1 isschematically shown in the form of a stand alone commercial counter topcooking appliance. As used herein, the term “commercial” includes, butis not limited to, the commercial food service industry, restaurants,fast food establishments, speed service restaurants, convenience stores(to list a few) and other mass feeding establishments and the term“residential” refers, generally speaking, to residential applications(home use), although the term is not limited to residences only, butrefers to non-commercial applications for the speed cooking oven.

Appliance 1 includes an oven cavity 2 generally defined by, FIG.2, a topwall 3, a bottom wall 4, left side wall 5 a right side wall 6, and FIG.4, a back wall 94 and a front wall 95. Oven cavity 2 also has associatedtherewith an access opening 7, FIG. 4, through which food items 10 maybe placed within oven cavity 2 upon cooking rack 8 a, FIG. 2. Althoughthe exemplary embodiment is shown as a countertop oven with one rack 8a, supported by side walls 5 and 6, it is obvious to one skilled in theart that the oven may be made with multiple racks and multiple gasdelivery systems, and is not limited to a single rack design. As usedherein, the term “gas” refers to any fluid mixture, including air andnitrogen that may be used in cooking processes and applicant intends toencompass within the language any structure presently existing ordeveloped in the future that performs the same function. Although thecooking rack 8 a is shown as supported by side walls 5 and 6, it isobvious to one skilled in the cooking art that rack 8 a may be afree-standing cooking rack not supported by the side walls. Cookingappliance 1 has a hinged door 9, FIG. 4, pivotally attached to the ovenfront for closing the cooking section opening 7 during cookingoperation. Hinged door 9 may be swung between an open position whereinthe door allows access to oven cavity 2 and a closed position whereinthe door covers the opening into oven cavity 2. Although illustrated asa hinged door pivotally attached at the left side of the front of theoven, the door may be hinged on the right side, bottom side or top side.

The speed cooking oven is comprised of two independent gas transfersystems, described herein as a left gas transfer system and a right gastransfer system, wherein left gas transfer system delivers gas to andfrom the left side of the oven cavity 2, and right gas transfer systemdelivers gas to and from the right side of the oven cavity 2. Ovencavity 2 also has associated therewith vent tube 71, FIG. 4, whichallows for the passage of vent gas from oven cavity 2 to atmosphere.Affixed within vent tube 71 is odor filter 72 which provides for theremoval of odors caused by the cooking process. Odor filter 72 may bemade to be removable for cleaning or replacement. Various materials maybe utilized to accomplish odor removal and varying efficiencies of saidmaterials may also be employed. For example, in some instances it may bedesirable for the odor filter to completely (as much as is possible)filter all odors while at other times it may be desirable to provide fora less efficient odor filter 72 in order to allow for the passage ofsome cooking odors. It has been found that during the cooking process,for example baking bread, the operator has an expectation of smellingbread cooking and it may not be desirable to completely filter allodors.

Referring to FIG. 4, gas is transferred to and from oven cavity 2 via aleft gas transfer system, which is comprised of a left gas transfersection 15 a, which extends from the front to back of oven top wall 3,along the left side of top wall 3. In fluid connection with left gastransfer section 15 a is top gas egress opening 12, which is open to,and in fluid connection with oven cavity 2 through top wall 3. Top gasegress opening 12 is substantially rectangular, although othergeometries may be employed, and is centrally located within oven topwall 3 and provides for the passage of gas from oven cavity 2 into leftgas transfer section 15 a, as gases are removed from oven cavity 2through top egress gas egress opening 12. Located within left gastransfer section 15 a is left grease extractor 13 a. As gas is drawnthrough top gas egress opening 12, the gas passes across left heatingmeans 14 a, prior to entry in and through left grease extractor 13 a.Heating means 14 a may include direct fired thermal energy, indirectfired thermal energy, propane, natural gas, electric resistance heatingelements, and other thermal means; and applicant intends to encompasswithin the language any structure presently existing or developed in thefuture that performs the same function. After the gas is drawn acrossheating means 14 a and through left grease extractor 13 a, it is thendrawn through left odor filter 40 a and into left gas transfer section15 a. Alternate locations for left odor filter 40 a can be utilizedwithin the gas flow path and the location of the left odor filteradjacent to left grease extractor 13 a is not required. In fluidconnection with, and located within left gas transfer section 15 a is aleft gas accelerator, illustrated as left blower wheel 16 a. Otherdevices may be utilized to accelerate the gas flow, such as acompressor, and applicant intends to encompass within the language anystructure presently existing or developed in the future that performsthe same function as 16 a, 90 a, 91 a and 16 b, 90 b and 91 b, to bediscussed further herein. Connected to left blower wheel 16 a is blowermotor shaft 90 a, which is direct drive with electric motor 91 a. Othermeans may be employed for coupling blower wheel 16 a to electric motor91 a, such as belt drive and the means is not limited to direct drive.Blower wheel 16 a takes gas from oven cavity 2 and delivers the gas viagas transfer section 17 a to the left top side of oven cavity 2. Topleft gas transfer section 17 a, FIG. 2, is in fluid connection with alower left gas transfer section 18 a via a left vertical gas transfersection 19 a. Left vertical gas transfer section 19 a is bounded by leftside wall 5 and a left microwave waveguide section 20 a. As can be seenin FIG. 2, as gas is pumped into top left gas transfer section 17 a, thegas is discharged through a top left discharge plate 23 a into ovencavity 2 via apertures 100 a and onto the left top and side portion offood product 10. Apertures 100 a may be slotted, regularly formed orirregularly formed apertures and are illustrated herein as nozzles 100 aand 29 a and applicant intends to encompass within the language anystructure presently existing or developed in the future that performsthe same function as 100 a, 29 a and 100 b and 29 b, discussed furtherherein. Gas that has not been discharged through top left gas dischargeplate 23 a flows to lower left gas transfer section 18 a via verticaltransfer section 19 a. Gas that is distributed to lower left gastransfer section 18 a may be re-heated, if desired, by a lower leftheating means 103 a, shown in FIG. 2, before said gas passes throughslotted or perforated lower left gas discharge plate 27 a via apertures29 a, for discharge onto the left bottom and left side portions of foodproduct 10 in oven cavity 2. Lower left heating means 103 a may bepresent in some embodiments and not present in others depending upon theparticular requirements for the speed cook oven. Apertures 100 a and 29a are sized for a low pressure drop, while providing and maintainingsufficient gas velocities in the range of approximately 2000 ft/minuteto approximately 6000 ft/minute to properly cook the food product asdescribed herein. In some instances, velocities below 2000 ft/minute andabove 6000 ft/minute may also be utilized. As shown in FIG. 6, apertures100 a are sized such that the majority of the gas is supplied from thetop left gas discharge plate 23 a. The resulting imbalance of gas flowsbetween the top left gas discharge plate 23 a and lower left gasdischarge plate 27 a is desirable because the top flows mustaggressively remove moisture produced and escaping from the top and topside surface of the food product 10. The imbalance also serves to heat,brown and/or heat and brown the food product 10.

Referring again FIG. 4, gas is also transferred to and from oven cavity2 via a right gas transfer system, which is comprised of a right gastransfer section 15 b, which extends from the front to back of oven topwall 3, along the right side of top wall 3. In fluid connection withright gas transfer section 15 b is top gas egress opening 12, which isopen to, and in fluid connection with oven cavity 2 through top wall 3.Top gas egress opening 12 is substantially rectangular, although othergeometries may be employed, and is centrally located within oven topwall 3 and provides for the passage of gas from oven cavity 2 into rightgas transfer section 15 b, as gases are removed from oven cavity 2through top egress gas egress opening 12. Located within right gastransfer section 15 b is right grease extractor 13 b. As gas is drawnthrough top gas egress opening 12, the gas passes across heating means14 b, prior to entry in and through right grease extractor 13 b. Afterthe gas is drawn across heating means 14 b and through right greaseextractor 13 b, it is then drawn through right odor filter 40 b and intoright gas transfer section 15 b. Alternate locations for right odorfilters 40 a, 40 b can be utilized within the gas flow path and thelocation of the right odor filter adjacent to right grease extractor 13b is not required. In fluid connection with, and located within rightgas transfer section 15 b is a right gas accelerator, illustrated asright blower wheel 16 b. Connected to right blower wheel 16 b is blowermotor shaft 90 b, which is direct drive with electric motor 91 b. Othermeans may be employed for coupling blower wheel 16 b to electric motor91 b, such as belt drive and the means is not limited to direct drive.Blower wheel 16 b takes gas from oven cavity 2 and delivers the gas viagas transfer section 17 b to the right top side of oven cavity 2.Although illustrated as a conventional blower motor, blower motor shaftand blower wheel, other gas pumping means such as a compressor may beutilized to re-circulate gas to and from oven cavity 2 and the inventionis not limited to use of a blower motor and blower wheel combination.Top right gas transfer section 17 b is in fluid connection with a lowerright gas transfer section 18 b via a right vertical gas transfersection 19 b. Right vertical transfer section 19 b is bounded by rightside wall 6 and a right microwave waveguide section 20 b. As can be seenin FIG. 2, as gas is pumped into top right gas transfer section 17 b,the gas is discharged through a top right discharge plate 23 b into ovencavity 2 via apertures 100 b and onto the right top and side portion offood product 10. Apertures 100 b may be slotted, regularly formed orirregularly formed apertures and are illustrated herein as nozzles 100 band 29 b. Gas that has not been discharged through top right gasdischarge plate 23 b flows to lower right gas transfer section 18 b viavertical transfer section 19 b. Gas that is distributed to lower rightgas transfer section 18 b may be re-heated, if desired, by a lower rightheating means 103 b, shown in FIG. 2, before said gas passes throughslotted or perforated lower right gas discharge plate 27 b via apertures29 b, for discharge onto the right bottom and right side portions offood product 10 in oven cavity 2. Lower right heating means 103 b may bepresent in some embodiments and not present in others depending upon theparticular requirements for the speed cook oven. Apertures 100 b and 29b are sized for a low pressure drop, while providing and maintainingsufficient gas velocities in the range of approximately 2000 ft/minuteto approximately 6000 ft/minute but as discussed with the left side gasdelivery system, velocities below 2000 ft/minute and above 6000ft/minute may be utilized if desired to properly cook the food productas described herein. As shown in FIG. 6, apertures 100 b are sized suchthat the majority of the gas is supplied from the top right gasdischarge plate 23 b. The resulting imbalance of gas flows between thetop right gas discharge plate 23 b and lower right gas discharge plate27 b is desirable because the top flows must aggressively removemoisture produced and escaping from the top and top side surface of thefood product 10. The imbalance also serves to heat, brown and/or heatand brown the food product 10.

The left and right gas supply systems, although independently describedherein, are the same configuration and function to uniformly circulatehot gas flow across the top and top sides and bottom and bottom sides ofthe food product, and return the gas to the heating mechanism forre-delivery to the cooking cavity.

As described, the gas flow is delivered via four gas transfer sections17 a, 17 b, 18 a, 18 b which are located in the top and bottom comers ofoven cavity 2 as shown in FIG. 2. Gas flow transfer sections 17 a, 17 b,18 a and 18 b extend from the back wall 94 of oven cavity 2 to the frontwall 95 of oven cavity 2, although it is not required that the gas flowtransfer sections extend the entire depth (front to back) of the ovencavity. Gas transfer section 17 a is located in the top left comer ofoven cavity 2 where top wall 3 intersects oven cavity side wall 5; gastransfer section 17 b in the top right corner where top wall 3intersects right side wall 6; gas transfer section 18 a in the lowerleft corner of the oven cavity where bottom wall 4 intersects left sidewall 5; and gas transfer section 18 b in the lower right corner wherebottom wall 4 intersects right side wall 6. Each of the gas transfersections are sized and configured to deliver the appropriate gas flowfor the particular oven utilized. For example, in a smaller oven, thegas delivery sections, indeed the entire oven, may be sized smaller inproportion to the smaller footprint of the particular requirements, anda larger oven will have proportionally larger gas delivery sections. Asseen in FIG. 6, the left side and the right side gas flows converge onthe food product 10 thereby creating an aggressive flow field on thefood product surface that strips away the moisture boundary layer. Thisturbulently mixed gas flow directed at the food product can best bedescribed as glancing, conflicting and colliding gas flow patterns thatspatially average the gas flow over the surface area of the food productproducing high heat transfer and moisture removal at the food surface,thereby optimizing speed cooking. The gas flow is directed towards thetop, the bottom and the sides of the food product from the left andright sides of the oven cavity and the left and right side gas flowsconflict, collide and glance off each other at the food product surfacebefore exiting the oven cavity through top gas egress opening. As usedherein the term “mixing” refers to the glancing, conflicting andcolliding gas flow patterns that meet at and upon the top surface, thebottom surface and the left and right side surfaces of the food productand produce high heat transfer and speed cooking of the food product dueto spatial averaging of the gas flow heat transfer. As used herein, theterms “mix”, “mixing”, “turbulent mix” and “turbulent mixing”.

The oven of the present invention does not require smooth gas flow,laminar gas flow or air wrap gas flow. The mixing gas flows patterns arecreated within the oven cavity and, when appropriately directed anddeflected, produce a high quality cooked food product very quickly.Enhancing the highly agitated, glancing, conflicting, and colliding gasflow of the present invention is the general upward flow path the gaswill follow, as shown in FIG. 6 a and 6 b, through top gas egressopening 12, as the gas exits the top of oven cavity 2. This upward gasflow draws also the gas from lower gas discharge sections 18 a and 18 bthereby scrubbing the bottom of the food product, pot, pan or othercooking vessel, by pulling gas flow around the sides of said vessel,further enhancing the heat transfer, as well as drawing the gas thatscrubs the upper surface up towards the oven cavity top wall.

Returning to FIG. 2, top gas discharge plates 23 a and 23 b arepositioned within oven cavity 2 such that the gas flow from top gastransfer section 17 a conflicts and collides with the gas flow from topgas transfer section 17 b upon the food product surface and strikes thefood product at an angle that is between zero degrees and 90 degrees asreferenced from the horizontal top wall (where zero degrees is parallelto the horizontal top wall) and lower gas discharge plates 27 a and 27 bare positioned within oven cavity 2 such that the gas flow from lowergas transfer section 18 a conflicts and collides with the gas flow fromlower gas transfer section 18 b upon the lower surface of the foodproduct at an angle that is between zero degrees and ninety degrees asreferenced from the horizontal bottom wall. Various cooking requirementsmay require that the angles of the gas discharge plates 23 a, 23 b, 27 aand 27 b be adjusted, either during manufacture, or adjustable withinthe unit after manufacture, in order for the chef or cook to change gasflow velocity angles (vectors) to effect different cooking profiles.

The number and placement of the apertures 100 a, 100 b, 29 a and 29 bwill vary according to the particular oven that is required. Asdescribed herein, this invention is “scalable” and as used herein theterm scalable has the meaning that the technology will provide for aplatform of products, not merely one particular size or one particularproduct. If, for example, a speed cooking baking oven were desired (asopposed to a general purpose speed cooking oven which cooks proteins,baked products, etc.) the apertures may be larger, but fewer in number.This would allow for a more gentle gas flow field across the foodproduct, and therefore more delicate baking of the food product. If abrowning oven were desired, the apertures may be more numerous andsmaller in diameter. Additionally, the operator may desire flexibilityof cooking and in this circumstance, gas discharge plates 23 a, 23 b, 27a and 27 b may be fabricated in a manner that allows for change-out ofthe plates. As used herein the term aperture refers to irregular slots,irregular holes or irregular nozzles, regularly formed slots, regularlyformed holes or regularly formed nozzles or a mixture of regularlyformed and irregularly formed slots, holes or nozzles. FIG. 2illustrates the use of three rows of apertures 100 a and l00 b on thetop side gas flow systems, gas delivery sections 17 a and 17 b, and tworows of apertures on the lower side gas flow systems 18 a and 18 balthough more rows and numbers of apertures or fewer rows and numbers ofapertures may be utilized for sections 17 a, 17 b, 18 a and 18 b.

The gas delivery system as illustrated in FIG. 6 produces aggressiveglancing, conflicting and conflicting gas flow patterns 30 a and 30 bwherein a gas flow is directed onto the top surface of the food product.An aggressive top glancing, conflicting and colliding gas flow pattern30 a also interacts with the left top portion and left top side portionof food product 10 and a similar right top glancing, conflicting andcolliding gas flow pattern 30 b interacts with the right top portion andtop right side portion of food product 10. As seen in FIG. 6 a, gas flowis also directed to the lower gas transfer sections 18 a and 18 b. Assuch, an aggressive glancing, conflicting and colliding gas flowpatterns 31 a and 31 b interact with the lower left and right portionsof the food product. This cooking profile creates high heat transfercapability by using the irregular surface of the food product, as wellas the interference of flow fields to minimize boundary layer growth. Asseen in FIG. 5, the angle of the gas flow velocity vector leaving thetop left and top right discharge plates 23 a and 23 b respectively, andthe bottom left and bottom right discharge plates 27 a and 27 brespectively, is between zero degrees and 90 degrees from horizontalbottom wall 4. After the aggressive glancing and conflicting gas flowpatterns 30 a and 30 b contact or strike the food product they areexhausted through top egress section 12 and cycle back through the ovenas described herein.

The gas flows within the oven, as well as other functions of cookingappliance are directed by controller 34, FIG. 2. Controller 34determines, among other things, the velocity of gas flow, which may beconstant or varied, or, may be constantly changed throughout the cookingcycle. It may be desired to cook the food product on one velocitythroughout the entire cooking cycle, or to vary the gas velocitydepending upon conditions such as a pre-determined cooking algorithm, orvary the velocity in response to various sensors that may be placedwithin the oven cavity, oven return air paths or various other positionswithin the oven. The location and placement of said sensors will bedetermined by the particular application of the oven. Additionally,other means may be utilized wherein data is transmitted back tocontroller 34, and thereafter controller 34 adjusts the cooking in anappropriate manner. For example sensors (temperature, humidity,velocity, vision and airborne chemical mixture level sensors) may beutilized to constantly monitor the cooking conditions and adjust the gasflow accordingly within a cooking cycle, and other sensors not describedherein may also be utilized. The speed cooking oven may utilize sensorsthat are not currently commercially utilized (such as laser,non-invasive temperature sensors and other sensors that are currentlytoo expensive to be commercially feasible), and the speed cooking ovenis not limited to those discussed herein, as many sensing devices areknown and utilized in the cooking art.

The gas flow performance may also be adjusted as a function of availablepower. In the event, for example, the heating system in an all electricspeed cooking oven is requiring or utilizing a large amount of power(larger than available power levels which may vary according to locationand local code and ordinance) it may be desirable for the controller toreduce electrical power to the convection beaters or other electricalcomponents accordingly in order to conserve available power. Indeed, incertain parts of the world where power is limited or capped, for exampleJapan and Italy, the oven of the present invention can be designed toadjust to these limiting conditions. In a speed cooking gas fired unit,some systems will be powered by electric current, but the electric powerrequirements will not be as high as required for an all electric ovenbecause the energy required for gas heating and cooking will be providedby the combustion of a hydrocarbon based fuel. In this event acontroller may not be required, indeed knobs or dials may be utilized.

Managing the gas flow pattern in a speed cooking oven is importantrelative to controlling the local convection heat transfer rate at thefood product. Many food products cooked in a typical rapid cook ovenrequire that the energy into the food (whether the energy be microwave,impingement gas, halogen light or other energy) be “tailored”(distributed) over the entire cooking cycle. This tailoring ormodulation of both the microwave and the convection energy systems is animportant feature in achieving a rapidly cooked food product with highfood quality. For example, a food product such as a pizza may require asmuch as 30 minutes to cook in a conventional oven, but can be cooked inas little as 3 minutes in a speed cooking oven. During this three minutecooking cycle, the controller may be programmed with an overall routineof cooking instructions that is broken down into sub-routines or events.As such, in a cooking profile, several different “sub-routines” may beutilized to attain the final rapidly cooked food product. The cook cyclemay, for example begin with 20 seconds of high velocity gas flow whereinthe gas flow is delivered at 100% velocity and the microwave output is10% of total microwave capacity. This cycle may then, for example, befollowed with 10 seconds of cooking time wherein 10% gas flow isutilized and no microwave power is used. This may then be followed by 1minute wherein 100% gas flow and 100% microwave power is used, followedby, for example, one minute wherein 50% microwave power is used and 50%gas flow is utilized. These speed cooking ovens therefore require asophisticated control mechanism that is expensive and can be a source ofreliability problems and variable speed blowers have therefore been usedin order to control, for example, vertical impingement air flow and aspreviously described, this approach is expensive because dynamicallybraking speed variable blower motor speed controllers are required,adding complexity and cost to the appliance. In addition, using air flowrates that vary from low flows to high flows requires “over-design” ofoven components such as convection heaters, grease control systems,blowers, blower motor controllers and nozzle plates because the partsmust work equally well together at low flow conditions as well as athigh flow conditions.

Although the present invention may utilize variable speed blower motorsand variable speed blower motor controllers, there is no requirement fortheir use and the speed cooking oven of the present invention avoidsthese problems, and the complexity of the variable speed blower motors,by maintaining a substantially constant gas glow rate through the ovencavity, gas transfer and gas delivery sections. FIG. 6 shows twoillustrative gas flow patterns wherein aggressive gas flow patterns 30 aand 30 b are shown and less aggressive gas flow patterns 31 a and 31 bare illustrated in FIG. 6 b. One means to achieve this gas flow patternmodification is by use of a gas pumping means, in this illustration, ablower motor, blower wheel combination, utilizing a controller or amulti speed switch that allows for the switching of the blower motorspeed in pre-determined fixed increments. Heating of the convection gasis provided by either electric resistance heating means 14 a and 14 b orby a direct fired (product of combustion mix with oven gas) means. Theheater is configured such that it can be operated at a lower heat fluxfor the convection heating and cooking mode, or at a higher rate forradiant heating and cooking. The radiant heating will also provideconvection heat for cooking. The purpose of the radiant feature is toprovide additional surface browning.

The speed cooking process produces a high grease generation rate becausethe amount of grease or liquids that are produced during a rapid cookoperation is approximately the same as conventional cooking, but thegrease load is produced in ⅕^(th) to 1/7^(th) and in some instances1/10^(th) the time of conventional cooking times. This results in highgrease loading (e.g. ounces/minute) of the gas flow stream which, if nottreated, may cause a number of problems including (a) smoke generation,as grease particles impact hot surfaces, (b) soiling of interior gastransfer and delivery surfaces, which may be bidden and difficult toclean, and (c) grease contamination of the food product itself from there-circulated air flow. Impingement style air flow amplifies this effectby throwing or entraining grease and other liquids that ultimatelycollect in the grease catch container around the food product. The gasflow of the present invention greatly reduces this effect by notallowing the gas flow to impinge on the liquid coated pan, cookingvessel or food surfaces. In order to control the grease and otherliquids produced by the speed cooking process, the first method employedis the particle removal of the grease. Grease in vapor form is much lessof an issue because there are no cool walls within the oven for vaporcondensation of the grease or liquid. Referring now to FIG. 2 and FIG.4, left grease extractor 13 a and right grease extractor 13 b arepositioned downstream of left thermal heating means 14 a and rightthermal means 14 b respectively. The gas flow passes over left and rightthermal means 14 a and 14 b before passing through left and right greaseextractors 13 a and 13 b. In order to control grease and other liquidparticles, grease extractors 13 a and 13 b are designed, FIG. 9 b, toprovide a convoluted gas flow path, 80 wherein the average flow velocitymaintained is in the approximately 2000 ft/minute to approximately 6000ft/min range. This method will extract a substantial amount of thegrease particles with mean diameters greater than approximately 3.0micrometers. Grease extractors 13 a and 13 b have a proximal end towardsthe front of oven cavity 2 and a distal end towards the back wall ofoven cavity 2 wherein the distal end is positioned slightly lower thanthe proximal end to allow grease to flow by means of gravity to the backwall of oven cavity 2 where it is collected within a grease collectionmeans 50, FIG. 9 a, or otherwise removed completely from the oven via atube, channel or other means that allows the liquid grease to collect ina collection device separate and apart from the speed cooking oven.Grease extractors 13 a and 13 b consist of a series of baffles ortroughs 81 that rapidly accelerates (change of direction) the flow 80 asthe gas flow bends around the flow diverters. Larger or heavier greaseparticles with the highest inertia cannot be sufficiently accelerated tofollow the flow as the flow passes through the diverters. As a result,the grease particles impact the diverter walls. The collection point isthe valley or trough, which both prevents re-entrainment of the greaseinto the air stream and also acts as a grease channel to remove greasefrom the oven cook cavity. This aerodynamic method of grease removalrelies on the pressure drop associated with the turning of the flowthrough the baffles. This design achieves approximately 90% removalefficiency of 3 micrometer or greater grease particles, while requiringless than approximately 1.5 inches of water column gas flow pressuredrop across the grease particle removal sections 13 a and 13 b. The flowarea restriction is designed to accelerate the gas flow prior to theflow diverters and to slow the gas flow after said flow exits thevalleys of the trough.

The most efficient utilization of the spent hot gas is by re-circulationof the gas flow through the oven cavity many times during a cookingcycle. During normal speed cooking it may be desirable for one foodproduct to be cooked after another different type of food product (fishfollowed by pastry) with successive cycles continuing. For exampleshrimp may be cooked first, followed by a baked product or pastry.Without appropriate filtration, the odors from the shrimp willcontaminate the baked product, producing an undesirable taste and odorin the pastry. There exists a need for further air clean-up (in additionto the grease extractors) to further scrub the gas flow of the particlesthat are not entrained by grease extractors 13 a and 13 b. In instanceswherein further filtration of the gas flow is desired, odor filters maybe placed within the oven cavity. FIG. 2 illustrates the use of odorfilters 40 a and 40 b for this purpose. Left side odor filter 40 a isattached within top left gas transfer section 17 a, downstream of leftgrease extractor 13 a and right odor filter 40 b is attached withinright gas transfer section 17 b downstream of right grease extractor 13b. Odor filters 40 a and 40 b are attached in a manner that allows fortheir easy removal for cleaning and replacement. Gas that flows into theleft and right gas transfer systems 15 a and 15 b first passes throughodor filters 40 a and 40 b. The gas flow is therefore further scrubbedafter passage through grease extractors 13 a and 13 b in order toeliminate odors that could interfere with the proper taste of the foodproduct currently being cooked. In some cases it may be beneficial toutilize a second set of odor filters, and these filters may be placedanywhere within the gas flow path downstream of blower wheels 16 a and16 b. Odor filers 40 a may be catalytic type elements or otherfiltration means including, but not limited to activated charcoal,zeolite or ultra violet wavelight light. It is beneficial that the odorfilters be comprised of a material, or materials, that effectivelyscrubs, or cleans the gas flow with a minimal amount of interferencewith the gas flow velocities. Additionally, it is beneficial that theodor filters be easily removed, easily cleaned and inexpensive for theoperator to replace.

The oven of the present invention may also utilize microwave energy toat least partially cook the food product. As seen in FIG. 2, left sidemicrowave launching waveguide 20 a is attached within oven cavity 2 toleft side wall 5 between top left gas transfer section 17 a and lowerleft gas transfer section 18 a. Right side microwave launching waveguide20 b is attached within oven cavity 2 to right side wall 6 between topright gas transfer section 17 b and lower right gas transfer section 18b. The microwave waveguides are designed to distribute microwave poweruniformly from the back to the front of oven cook cavity 2. As shown inFIG. 8, such a configuration promotes uniform illumination of microwaveenergy to the right side and the left side of the cook chamber becausethe microwave energy from the side walls is additive over the product.The vertical distance above cavity bottom wall 4 of waveguides 20 a and20 b is such that, under normal cooking conditions, approximately morethan ⅓% of the microwave energy is available below cooking rack 8 a,with the balance of microwave energy available above cooking rack 8 a.

Metal cooking devices such as cooking pans, cookie sheets and othermetal cookware is traditionally used in conventional cooking. Becausemicrowave energy cannot penetrate these metal devices, all of themicrowave energy must enter the top and side surfaces of the foodproduct. To overcome the issue that metal pans create, some ovensutilize a top launch microwave system. The theory has been to providemicrowave energy through the top surface of the food product, but thisapplication of microwave power applies excessive microwave energy to thetop of the product, causing over cooking, producing a tough, rubberyfood product. The overcooking problem is especially acute when cookingproteins, such as meat. In order to prevent this microwave overcookcondition, one method historically utilized was a reduction of themicrowave energy that is available for cooking the food product. Theresult of limiting the microwave energy to the food product is that themicrowave energy is more evenly distributed over the cook cavity, butthis reduction in applied microwave energy results in a slower cookprocess, defeating the desire for a speed cooking oven.

Other methods of distributing microwave energy launch microwave energyfrom below the food product. This is not optimum because microwaveenergy that is to enter the upper surface of the food product mustbounce around within the oven cavity in a random and inefficient mannerin order to enter the top side of the food. As shown in FIG. 11,microwave energy is broadcast from waveguide 20 a into oven cavity 2 viaa slotted antenna 70 wherein three or four narrow apertures (slots) 70a, 70 b, 70 c, 70 d are spaced along the waveguide. Variousconfigurations for microwave distribution have been utilized withvarying results. Food product 10 is placed within oven cavity 2 adistance of at least 2.4 inches (for optimal cooking uniformity) fromleft side wall 5 and right side wall 6. The 2.45 inch measurementcorresponds to one half a microwave wavelength or 2.4 inches (foroptimal cooking uniformity) (E field null) for a 2.45 GHz microwave tube(microwave) frequency. This spacing permits the E-field 51 a and 51 bFIG. 8, to expand and become more uniform prior to coupling with thefood product.

The right side microwave system is identical to the left side system andmicrowave energy is broadcast from right waveguide 20 b to oven cavity 2via a slotted antenna as previously described for the left side. Themicrowave energy field therefore propagates through the oven cavity inan evenly distributed pattern, coupling with the food product from alldirections, and providing an even electromagnetic energy distributionthroughout the oven cavity without the need for a mechanical stirrer topropagate the electromagnetic field.

Waveguides 20 a and 20 b are located on the left and right side walls ofthe oven, and therefore do not interfere with oven cavity spent gasexhaust.

The microwave waveguides are located on the side walls of the ovencavity, and are not affected by food spills, grease contamination,cleaning fluid contamination or other contamination that normally affecta bottom launch microwave system. The microwave system of the presentinvention will therefore be less likely to be penetrated by grease,spills, cleaning materials and other contaminants because the systemsare not located directly under the food product where hot contaminantswill drip.

As seen in FIG. 2, bottom wall 4 has a smooth, continuous bottom that iseasy to clean with no heating elements, air return ducts or microwavelaunchers within the oven cavity floor. In instances where air returnmeans, heating elements and microwave launchers protrude through theoven floor it is very difficult for an operator to clean and maintainthe oven in a sanitary condition. In a bottom launch microwave system,the waveguide launcher is generally located within the center portion ofthe oven cavity bottom wall. As grease, oils and other by-products ofthe cooking process are released during normal cooking, they drip andsplatter onto the microwave launcher. The launcher must be protected andis covered with a microwave transparent material such as quartz andsealed with adhesives or other sealants in an effort to preventcontaminants from entering the launcher, causing pre-mature breakdown ofthe magnetron. Additionally, some speed cook ovens have located upon thebottom wall a radiant element to assist with bottom side browning. Forcommercial applications an exposed lower radiant element may result insafety issues as grease builds up around the hot element.

The present invention utilizes a smooth oven cavity floor that does notallow for the contamination of the microwave system, the gasre-circulating system or the wave guide launcher by grease and other byproducts of the cooking process that drip or spill from the cookingcontainers. Gas discharge plates 23 a and 23 b, FIG. 2, are located inthe corners of the oven with the apertures 29 a, 29 b located above theoven floor. The microwave launching system is affixed between gastransfer sections 17 a and 17 b on the left side and 18 a and 18 b onthe right side. As such, the bottom of the oven cavity is left as acontinuous, unencumbered surface. Apertures 29 a and 29 b are positionedabove oven bottom wall 4 and cleaning of the oven floor is thereforeeasily achieved. Additionally, plates 27 a and 27 b can be manufacturedto be removable from lower gas transfer sections 18 a and 18 b forcleaning or replacement. Radiant elements 103 a and 103 b, are locatedwithin gas transfer sections 18 a, and 18 b and will therefore not becontaminated by food spills, grease and cooking by-products thatsplatter and drop from the cooking rack.

Although the present invention has been described in considerable detailwith reference to certain preferred versions thereof, other versions arepossible. For example, various sizes of commercial and residential speedcooking ovens may be made. In these cases larger or smaller componentparts may be utilized and fewer or more components may be employed. Inthe case where it is desirable to make a smaller speed cooking oven, onegas flow acceleration means may be utilized instead of two; onemicrowave system utilized instead of two; smaller or fewer thermaldevices, whether electric resistance or gas fired may be used. In caseswherein it is desirable for a larger speed cooking oven, multiple rackunits may be developed and additional gas flow systems and microwavesystems may be added to accomplish a larger cavity, multi rack speedcooking oven. Other modifications and improvements thereon will becomereadily apparent to those skilled in the art. Accordingly, the spiritand scope of the present invention is to be considered broadly andlimited only by the appended claims, and not by the foregoingspecification.

Any element in a claim that does not explicitly state “means for”performing a specific function, or “step for” performing a specificfunction, is not to be interpreted as a “means” or “step” clause asspecified in 35 U.S.C. §112, ¶6. In particular, the use of “step of” inthe claims herein is not intended to invoke the provisions of 35 U.S.C.§112,

To summarize, the present invention provides for a speed cooking ovenutilizing hot gas flows, hot gas flows coupled with microwave energy inorder to achieve speed cooking of food products five to ten times fasterthan conventional cooking methods at quality, taste and appearancelevels that are equal to and exceed conventional cooking. The oven isoperable on standard commercial power and residential supplies and issimple and economical to manufacture, use and maintain, and is directlyscalable to larger or smaller commercial and larger or smallerresidential embodiments. The speed cooking oven may operate as a speedcooking air only oven, a microwave oven or a combination air andmicrowave speed cooking oven. Additionally, the invention may bepracticed wherein no gas diverters are utilized, such as in theexemplary embodiment, gas deflection means are utilized as in the secondembodiment, and the invention may also be scaled and an example of ascaled up unit has been provided as a multi rack oven. Many and variousother combinations are possible. For example, the embodimentsillustrated herein may utilize gas deflection means, or be practiced asillustrated in the exemplary embodiment with no gas deflection means.The invention may be practiced using various gas delivery means otherthan those illustrated herein.

Also, various sizes of commercial and residential speed cooking ovensmay be made and the invention is not limited to the embodimentsdescribed herein. In the instances wherein larger or smaller ovens areto be practiced, larger or smaller component parts may be utilized; andfewer or more components may be employed. In the case where it isdesirable to make a smaller speed cooking oven, one gas flowacceleration means may be utilized instead of two; one microwave systemutilized instead of two; smaller or fewer thermal devices, whetherelectric resistance or gas fired may be used. In cases wherein it isdesirable for a larger speed cooking oven, multiple rack units may bedeveloped and additional gas flow systems and microwave systems may beadded to accomplish a larger cavity, multi rack speed cooking oven.Apertures may be made larger or smaller depending upon the gas flowrequirements of a practiced version. The heating means 14 a and 14 b maybe combined into one heating element, or more than two heating elementsmay be utilized.

Second Version

An second version of the speed cook oven with gas control and deflectingmeans is shown as a stand alone commercial cooking appliance with gasflow control, but it is obvious to those skilled in the cooking art thatthis stand alone speed cooking appliance may exist in many othercommercial and residential embodiments (e.g. counter-top oven,wall-oven, single rack oven, multi-rack oven) because the speed cookoven with gas flow control is scalable up or scalable down. As usedherein, the term “scalable” has the meaning that additional largercommercial and residential and smaller residential and commercialembodiments can be developed and the invention is not limited to acertain size or particular design. Of course each embodiment may havedifferent size characteristics and require different voltages ofelectricity—as commercial power supplies are generally different thanresidential power supplies. This speed cook oven is therefore notlimited to commercial uses only, and is equally applicable forresidential (home) use. With initial reference to FIGS. 11-15, a speedcook appliance 101 is schematically shown in the form of a stand alonecommercial counter top cooking appliance. As used herein, the term“commercial” includes, but is not limited to, the commercial foodservice industry, restaurants, fast food establishments, quick servicerestaurants, convenience stores (to list a few) and other mass feedingestablishments and the term “residential” refers, generally speaking, toresidential applications (home use), although the term is not limited toresidences only, but refers to non-commercial applications for the speedcooking oven.

Appliance 101 includes an oven cavity 102 generally defined by a topwall 103, a bottom wall 104, left side wall 105, right side wall 106, aback wall 194 and a front wall 195. Oven cavity 102 also has associatedtherewith an access opening 107 through which food items 110 may beplaced within oven cavity 102 upon cooking rack 108 a, FIG. 11. Althoughshown as a countertop oven with one rack 108 a, supported by side walls105 and 106, the invention may be practiced wherein multiple racks areutilized. Although the cooking rack 108 a is shown as supported by sidewalls 105 and 106, it is obvious to one skilled in the cooking art thatrack 108 a may be a free-standing cooking rack not supported by the sidewalls. Cooking appliance 101 has a hinged door 109 pivotally attached tothe oven front for closing the cooking section opening 107 duringcooking operation. Hinged door 109 may be swung between an open positionwherein the door allows access to oven cavity 102 and a closed positionwherein the door covers the opening into oven cavity 102. Althoughillustrated as a hinged door pivotally attached at the left side of thefront of the oven, the door may be hinged on the right side, bottom sideor top side.

Referring now to FIG. 12, the speed cooking oven is comprised of twoindependent gas transfer systems, described herein as a left gastransfer system and a right gas transfer system wherein left gastransfer system delivers gas to and from the left side of the ovencavity 102, and right gas transfer system delivers gas to and from theright side of the oven cavity 102. Although each gas transfer system isdescribed separately, the systems are identical in their configurationand operation and serve to distribute gas to the respective sides ofoven cavity 102. Oven cavity 102 also has associated therewith vent tube171, FIG. 12, which allows for the passage of vent gas from oven cavity2 to atmosphere. Affixed within vent tube 171 is odor filter 172, whichprovides for the removal of odors caused by the cooking process. Variousmaterials may be utilized for odor filter 172 and varying materials withvarying efficiencies may be utilized. For example, in some instances itmay be desirable for odor filter 172 to completely filter all odors,while at other times it may be desirable to provide for a less efficientodor filter 172 in order to allow for the passage of some cooking odors.It has been found that during the cooking process, for example bakingbread or cookies, the cook has an expectation of smelling bread cookingand it may not be desirable to completely filter all odors.

Gas is transferred to and from the left side of oven cavity 102 via aleft gas transfer system, which is comprised of a left gas transfersection 115 a, extending from the front to back of oven top wall 103,along the left side of top wall 103. In fluid connection with left gastransfer section 115 a is top gas egress opening 112, which is open to,and in fluid connection with oven cavity 102 through top wall 103. Topgas egress opening 112 is substantially rectangular, although othergeometries may be utilized, and is centrally located within oven topwall 103 and provides for the passage of gas from oven cavity 102 intoleft gas transfer section 115 a, as gases are removed from oven cavity102 through top egress gas egress opening 112. Located within left gastransfer section 115 a is left grease extractor 113 a. As gas is drawnthrough top gas egress opening 112, the gas passes across left heatingmeans 114 a, prior to entry in and through left grease extractor 113 a.Heating means 114 a may include a direct fired thermal energy source,indirect fired thermal energy, propane, natural gas, electric resistanceheating elements, and other thermal means, and applicant intends toencompass within the language any structure presently existing ordeveloped in the future that performs the same function. After the gasis drawn across left heating means 114 a and through left greaseextractor 113 a, it is then drawn through left odor filter 140 a andinto left gas transfer section 115 a. Alternate locations for left odorfilter 140 a can be utilized within the gas flow path and the locationof the left odor filter 140 a adjacent left grease extractor 113 a isnot required. In fluid connection with, and located within left gastransfer section 115 a is a left gas accelerator, illustrated as leftblower wheel 116 a. Connected to left blower wheel 116 a is blower motorshaft 190 a, which is driven by a direct shaft from electric motor 191a. Other means may be employed for coupling blower wheel 116 a toelectric motor 191 a, such as belt drive, and the means is not limitedto direct drive. Blower wheel 116 a takes gas from oven cavity 102 anddelivers the gas via gas transfer section 117 a to the left top side ofoven cavity 102. Although illustrated as a conventional blower motor,blower motor shaft and blower wheel, other gas pumping means such as acompressor may be utilized to re-circulate gas to and from oven cavity102 and applicant intends to encompass within the language any structurepresently existing or developed in the future that performs the samefunction. Top left gas transfer section 117 a is in fluid connectionwith a lower left gas transfer section 118 a via a left vertical gastransfer section 119 a. Left vertical transfer section 119 a is boundedby left side wall 105 and a left microwave waveguide section 120 a.

As gas is discharged into top left gas transfer section 117 a, aselected portion of said gas is directed into a top left dischargesection 121 a by a top left deflecting means 122 a, FIG. 13 shown in theopen position. Thereafter the gas is discharged through apertureslocated within a top left slotted or perforated discharge plate 123 a.Gas is then distributed into oven cavity 102. Apertures 100 a may beslotted, regularly formed or irregularly formed apertures and areillustrated herein as nozzles, 100 a and 129 a, to be discussed herein,and applicant intends to encompass within the language any structurepresently existing or developed in the future that performs the samefunction as 100 a, 29 a and to be discussed further herein 100 b and 29b. Gas is distributed through various apertures 100 a located withinleft discharge plate 123 a and delivered onto the left top and left sideportions of the food product 110. As gas enters top left gas deliverysection 121 a, said gas may be further deflected via a top left gasdeflecting means 124 a as shown in FIG. 13 in the open position. Gasdeflecting means 124 a is pivotally attached to gas discharge plate 123a, although, other means for accomplishing said gas deflection may beutilized. For example means such as normally open, normally closed, ornormally partially open and normally partially closed switched platesmay be used (wherein said plates slide along the inside of perforatedplate 123 a to limit the aperture openings 100 a of discharge plate 123a), and applicant intends to encompass within the language any structurepresently existing or developed in the future that performs the samefunction. Gas that has not been discharged or deflected into top leftgas delivery section 121 a by gas deflecting means 122 a flows to lowerleft gas transfer section 118 a via vertical transfer section 119 a.Pivotally attached to waveguide section 120 a is a lower gas transferdeflection mechanism 152 a, FIG. 13 that operates to limit the amount ofgas that is transferred to lower gas transfer section 118 a. As usedherein, the terms “flow control means” “gas deflecting means” “transferdeflection mechanism” and “flow control means” all have the same meaningand refer to means to control gas flow within the oven. Indeed, certainspeed cooking operations may call for more gas flow to the lower part ofthe speed cooking oven, while other operations will call for little orno gas flow to the bottom side of the oven for delivery to the bottom ofthe food product. In those instances where little or no gas flow isdesired upon the bottom surface of the food product, gas transferdeflection mechanism 152 a may be closed in order to allow all, orsubstantially all, of the gas flow into top left gas delivery section121 a.

Gas that flows to lower left gas delivery section 118 a may bere-heated, if required, by lower left heating means 126 a, FIG. 13.After passing over heating elements 126 a, the gas may be furtherdeflected by deflecting means 128 a, FIG. 13, shown in the openposition. As gas deflecting means 128 a is rotated, directional controlof the gas flow may be further refined, allowing for gas flow to passthrough the upper or lower rows of apertures of lower gas plate 127 a atvarious positions along food product 110 bottom surface, FIG. 14 b.Although gas deflecting means 128 a is shown as pivotally attached toleft slotted or perforated gas discharge plate 127 a, gas deflectingmeans 128 a is not limited to the pivotally attached means illustratedherein, and as described elsewhere herein, applicant intends toencompass within the language any structure presently existing ordeveloped in the future that performs the same function. Apertures 100a, 100 b, 129 a and 129 b are sized for low pressure drop, whileproviding and maintaining sufficient gas velocities of approximately2000 ft/minute to approximately 6000 ft/minute to properly cook the foodproduct, although velocities above 6000 ft/minute may be used andvelocities less than 2000 ft/minute may also be utilized. As shown inFIG. 14 a, the apertures are adjusted such that the majority of the gasis supplied from the top left gas discharge section 121 a. The resultingimbalance of gas flows between the top left gas flow 130 a and lowerleft gas flow 132 a is desirable because the top flow 130 a mustaggressively remove moisture produced and escaping from the top surface,and top side surface of food product 110. The imbalance also serves toheat, brown and/or heat and brown the food product 110.

Referring now to the right gas transfer system, FIG. 12, gas istransferred to and from oven cavity 102 via a right gas transfer system,which is comprised of a right gas transfer section 115 b, which extendsfrom the front to back of oven top wall 103, along the right side of topwall 103. In fluid connection with right gas transfer section 115 b istop gas egress opening 112, which is open to, and in fluid connectionwith oven cavity 102 through top wall 103. Top gas egress opening 112 issubstantially rectangular, although other geometries may be employed,and is centrally located within oven top wall 103 and provides for thepassage of gas from oven cavity 102 into right gas transfer section 115b, as gases are removed from oven cavity 102 through top egress gasegress opening 112. Located within right gas transfer section 115 b isright grease extractor 113 b. As gas is drawn through top gas egressopening 112, the gas passes across right heating means 114 b, prior toentry in and through right grease extractor 113 b. After the gas isdrawn across heating means 114 b and through right grease extractor 113b, it is then drawn through right odor filter 140 b and into right gastransfer section 115 b. Heating means 114 a and 114 b may be combinedinto one heating element, or more than two elements may be utilizeddepending upon the particular requirements of the oven, and applicantintends to encompass within the language any number of electricresistance heating elements that performs the same function. Alternatelocations for right odor filters 140 a, 140 b can be utilized within thegas flow path and the location of the right odor filter adjacent toright grease extractor 113 b is not required. In fluid connection with,and located within right gas transfer section 115 b is a right gasaccelerator, illustrated as right blower wheel 116 b. Connected to rightblower wheel 116 b is blower motor shaft 190 b, which is direct drivewith electric motor 191 b. Other means may be employed for couplingblower wheel 116 b to electric motor 191 b, such as belt drive and themeans is not limited to direct drive as described elsewhere herein andapplicant intends to encompass within the language any structurepresently existing or developed in the future that performs the samefunction. Blower wheel 116 b takes gas from oven cavity 102 and deliversthe gas via gas transfer section 117 b to the right top side of ovencavity 102. Although illustrated as a conventional blower motor, blowermotor shaft and blower wheel, other gas pumping means such as acompressor may be utilized to re-circulate gas to and from oven cavity102 and applicant intends to encompass within the language any structurepresently existing or developed in the future that performs the samefunction. Top right gas transfer section 117 b is in fluid connectionwith a lower right gas transfer section 118 b via a right vertical gastransfer section 119 b. Right vertical transfer section 119 b is boundedby right side wall 106 and a right microwave waveguide section 120 b.

As gas is discharged into top right gas transfer section 117 b, aselected portion of said gas is directed into a top right dischargesection 121 b by a top right deflecting means 122 b, shown in the openposition in FIG. 15. Thereafter the gas is discharged through a topright slotted or perforated discharge plate 123 b into oven cavity 102.Slotted or perforated right discharge plate 123 b is used to distributegas leaving top right gas delivery section 121 b through variousapertures 100 b into oven cavity 102 and onto the right top and sideportion of the food product 110. As gas enters top right gas deliverysection 121 b, said gas may be further deflected via a top right gasdeflecting means 124 b as shown in FIG. 15. Gas deflecting means 124 bis shown as pivotally attached to slotted or perforated discharge plate123 b, although other means for accomplishing said gas deflection may beutilized, and applicant intends to encompass within the language anystructure presently existing or developed in the future that performsthe same function. For example, the use of normally open, normallyclosed, or normally partially open and normally partially closedswitched plates may be used (wherein said plates slide along the insideof perforated plate 123 b to limit the aperture openings 100 b ofdischarge plate 123 b. Gas that has not been discharged or deflectedinto top right gas delivery section 121 b by gas deflecting means 122 bflows to lower right gas transfer section 118 b via vertical transfersection 119 b. Pivotally attached to waveguide section 120 b is a gastransfer deflection mechanism 152 b, shown in the open position, FIG.15, that operate to limit the amount of gas that is transferred to lowergas transfer section 118 b. Again, as with the left side gas transfersystem, certain speed cooking operations may call for more gas flow tothe lower part of the speed cooking oven, while other operations willcall for little or no gas flow to the lower part of the oven for bottomside browning of the food product. In those instances where little or nogas flow is desired upon the bottom surface of the food product, gastransfer deflection means 152 b may be closed, or partially closed, inorder to allow little or no gas flow to lower gas delivery section 118b.

Gas flow that that is distributed to lower right gas delivery section118 b may be re-heated, if required, by lower right heating means 126 b,FIG. 15. After passing over heating elements 126 b, which may or may notbe present in every oven, depending upon the particular ovenrequirements, the gas may be further deflected by deflecting means 128b, FIG. 15, shown in the open position. As gas deflecting means 128 b isrotated, directional control of the gas flow may be further refined,allowing for gas flow to pass through the upper or lower apertures oflower gas plate 127 b at various positions along food product 110 bottomsurface. Apertures 100 b and 129 b are sized for low pressure drop,while providing and maintaining sufficient gas velocities ofapproximately 2000 ft/min to approximately 6000 ft./minute to properlycook the food product although as with other oven functions, gas flowsabove 6000 ft/minute and lower than 2000 ft/minute may be utilized asneeded. Again, as shown in FIG. 14 a, the top apertures are adjustedsuch that the majority of the gas is supplied from the top right gasdischarge section 121 b. The resulting imbalance of gas flows betweenthe top right gas discharge section 121 b and lower right gas dischargesection 118 b is desirable because the top flow 130 b, FIG. 14 a, mustaggressively remove moisture produced and escaping from the top surfaceand top side surface of the food product 110. The imbalance also servesto heat, brown and/or heat and brown the food product 110.

As gas flow 130 a is directed toward the center of oven cavity 102 fromthe left side and gas flow 130 b is directed toward the center of ovencavity 102 from the right side, the gas flows meet upon the surface ofthe food product and turbulently mixes, causing high heat transfer andrapid cooking of the food product. This turbulently mixed gas flowdirected at the food product can best be described as glancing,conflicting and colliding gas flow patterns that spatially average thegas flow over the surface area of the food product producing high heattransfer at the food surface, thereby optimizing speed cooking. The gasflow is directed towards the top, the bottom and the sides of the foodproduct from the left and right sides of the oven cavity and the leftand right side gas flows conflict, collide and glance off each other atthe food product surface before exiting the oven cavity through top gasegress opening. As used herein the term “mixing” refers to the glancing,conflicting and colliding gas flow patterns that meet at and upon thetop surface, the bottom surface and the left and right side surfaces ofthe food product and produce high heat transfer and speed cooking of thefood product due to spatial averaging of the gas flow heat transfer. Asused herein, the terms “mix”, “mixing”, “turbulent mix” and “turbulentmixing”. The same mixing of gas flow occurs upon the lower surface andlower side surfaces of food product 110 by lower gas flows 132 a and 132b also shown in FIG. 14 a.

In those instances wherein directional control of the gas flow isdesired, gas deflecting means 122 a, 122 b, 124 a, 124 b, 128 a, 128 band 152 a and 152 b, FIG. 14 b may be rotated such that gas flow isdiverted to selected apertures, thereby effecting a different gas flowpattern and gas mixing upon the food product surface. Additionally, inthose instances wherein no bottom side gas flow is desired, gasdeflecting means 152 a, 152 b may be closed, thereby allowing for littleor no passage of gas flow to the lower portion of the oven cavity.Various other adjustments of gas deflecting means 122 a, 122 b, 124 a,124 a, 128 a, 128 b, 152 a, 152 b are possible and applicant intends toencompass within the language any structure presently existing ordeveloped in the future that allows for combinations of open and closedpositions by the various gas flow control means. Gas deflecting (flowcontrol) means 122 a, 122 b, 124 a, 124 b, 128 a, 128 b, 152 a and 152 bmay be manually controlled, automatically controlled via controller 134or some combination of automatic and manual control and applicantintends to encompass within the language any structure presentlyexisting or developed in the future that performs the function describedherein concerning adjustment of the gas deflecting means.

The gas flows and flow control within the oven, as well as otherfunctions of cooking appliance are directed by controller 134, FIG. 11.Controller 134 determines, among other things, the velocity of gas flow,which may be constant or varied, or, may be constantly changedthroughout the cooking cycle. It may be desired to cook the food producton one velocity throughout the entire cooking cycle, or to vary the gasvelocity depending upon conditions such as a pre-determined cookingalgorithm, or vary the velocity in response to various sensors that maybe placed within the oven cavity, oven return air paths or various otherpositions within the oven. The location and placement of said sensorswill be determined by the particular application of the oven.Additionally, other means may be utilized wherein data is transmittedback to controller 134, and thereafter controller 134 adjusts thecooking in an appropriate manner. For example sensors (temperature,humidity, velocity, vision and airborne chemical mixture level sensors)may be utilized to constantly monitor the cooking conditions and adjustthe gas flow accordingly within a cooking cycle, and other sensors notdescribed herein may also be utilized. The speed cooking oven mayutilize sensors that are not currently commercially utilized (such aslaser, non-invasive temperature sensors and other sensors that arecurrently too expensive to be commercially feasible), and the speedcooking oven is not limited to those discussed herein, as many sensingdevices are known and utilized in the cooking art.

The gas flow performance and flow control may also be adjusted as afunction of available power. In the event, for example, the heatingsystem in an all electric speed cooking oven is requiring or utilizing alarge amount of power (larger than available power levels which may varyaccording to location and local code and ordinance) it may be desirablefor the controller to reduce electrical power to the convection heatersor other electrical components accordingly in order to conserveavailable power. Indeed, in certain parts of the world where power islimited or capped, for example Japan and Italy, the oven of the presentinvention can be designed to adjust to these limiting conditions. In aspeed cooking gas fired unit, some systems will be powered by electriccurrent, but the electric power requirements will not be as high asrequired for an all electric oven because the energy required for gasheating and cooking will be provided by the combustion of a hydrocarbonbased fuel. In this event a controller may not be required, indeed knobsor dials may be utilized.

Managing the gas flow control and gas flow pattern in a speed cookingoven is important relative to controlling the local convection heattransfer rate at the food product. Many food products cooked in atypical rapid cook oven require that the energy into the food (whetherthe energy be microwave, impingement gas, halogen light or other energy)be “tailored” (distributed) over the entire cooking cycle. Thistailoring or modulation of both the microwave and the convection energysystems is an important feature in achieving a rapidly cooked foodproduct with high food quality. For example, a food product such as apizza may require as much as 30 minutes to cook in a conventional oven,but can be cooked in as little as 3 minutes in a speed cooking oven.During this three minute cooking cycle, the controller may be programmedwith an overall routine of cooking instructions that is broken down intosub-routines or events. As such, in a cooking profile, several different“sub-routines” may be utilized to attain the final rapidly cooked foodproduct. The cook cycle may, for example begin with 20 seconds of highvelocity gas flow wherein the gas flow is delivered at 100% velocity andthe microwave output is 10% of total microwave capacity. This cycle maythen, for example, be followed with 10 seconds of cooking time wherein10% gas flow is utilized and no microwave power is used. This may thenbe followed by 1 minute wherein 100% gas flow and 100% microwave poweris used, followed by, for example, one minute wherein 50% microwavepower is used and 50% gas flow is utilized. These speed cooking ovenstherefore require a sophisticated control mechanism that is expensiveand can be a source of reliability problems and variable speed blowershave therefore been used in order to control, for example, verticalimpingement air flow and as previously described, this approach isexpensive because dynamically braking speed variable blower motor speedcontrollers are required, adding complexity and cost to the appliance.In addition, using air flow rates that vary from low flows to high flowsrequires “over-design” of oven components such as convection heaters,grease control systems, blowers, blower motor controllers and nozzleplates because the parts must work equally well together at low flowconditions as well as at high flow conditions.

Although the present version with gas flow control may utilize variablespeed blower motors and variable speed blower motor controllers inaddition to manual or automatically controlled flow control, there is norequirement for their use and the speed cooking oven of the presentinvention avoids these problems, and the complexity of the variablespeed blower motors, by maintaining a substantially constant gas glowrate through the oven cavity, gas transfer and gas delivery sections.FIGS. 14 a and 14 b show two illustrative gas flow patterns. FIG. 14 aillustrates gas flow patterns wherein aggressive gas flow patterns 130 aand 130 b are top side gas flow and gas flow patterns 132 a and 132 bare bottom side gas flows. FIG. 14 b illustrates less aggressive topside gas flow patterns 131 a and 131 b and 133 a and 133 b. One means toachieve this gas flow pattern modification is by use of a gas pumpingmeans, in this illustration, a blower motor, blower wheel combination,utilizing a controller or a multi speed switch that allows for theswitching of the blower motor speed in pre-determined fixed increments.Heating of the convection gas is provided by either electric resistanceheating means 114 a and 114 b or by a direct fired (product ofcombustion mix with oven gas) means. The heater is configured such thatit can be operated at a lower heat flux for the convection heating andcooking mode, or at a higher rate for radiant heating and cooking. Theradiant heating will also provide convection heat for cooking. Thepurpose of the radiant feature is to provide additional surfacebrowning.

The speed cooking process utilizing gas flow control produces a highgrease generation rate because the amount of grease or liquids that areproduced during a rapid cook operation is approximately the same asconventional cooking, but the grease load is produced in ⅕^(th) to1/7^(th) and in some instances 1/10^(th) the time of conventionalcooking times. This results in high grease loading (e.g. ounces/minute)of the gas flow stream which, if not treated, may cause a number ofproblems including (a) smoke generation, as grease particles impact hotsurfaces, (b) soiling of interior gas transfer and delivery surfaces,which may be hidden and difficult to clean, and (c) grease contaminationof the food product itself from the re-circulated air flow. Impingementstyle air flow amplifies this effect by throwing or entraining greaseand other liquids that ultimately collect in the grease catch containeraround the food product. The gas flow of the present invention greatlyreduces this effect by not allowing the gas flow to impinge on theliquid coated pan, cooking vessel or food surfaces. In order to controlthe grease and other liquids produced by the speed cooking process, thefirst method employed is the particle removal of the grease. Grease invapor form is much less of an issue because there are no cool wallswithin the oven for vapor condensation of the grease or liquid.Referring now to FIG. 11 and FIG. 12, left grease extractor 113 a andright grease extractor 113 b are positioned downstream of left thermalheating means 114 a and right thermal means 114 b respectively. The gasflow passes over left and right thermal means 114 a and 114 b beforepassing through left and right grease extractors 113 a and 113 b. Inorder to control grease and other liquid particles, grease extractors113 a and 113 b are designed to provide a convoluted gas flow path, 80,FIG. 9 b wherein the average flow velocity maintained is in theapproximately 2000 ft/minute to approximately 6000 ft/min range,although velocities above the 6000 ft/minute and below the 2000ft/minute range may be employed. This method will extract a substantialamount of the grease particles with mean diameters greater thanapproximately 3.0 micrometers. Grease extractors 113 a and 113 b have aproximal end towards the front of oven cavity 102 and a distal endtowards the back wall 194 of oven cavity 102 wherein the distal end ispositioned slightly lower than the proximal end to allow grease to flowby means of gravity to the back wall of oven cavity 102 where it iscollected within a grease collection means 50, FIG. 9 a, or otherwiseremoved completely from the oven via a tube, channel or other means thatallows the liquid grease to collect in a collection device separate andapart from the speed cooking oven. Grease extractors 113 a and 113 bconsist of a series of baffles or troughs 81 FIG. 9 b, that rapidlyaccelerates (change of direction) the flow 80 as the gas flow bendsaround the flow diverters. Larger or heavier grease particles with thehighest inertia cannot be sufficiently accelerated to follow the flow asthe flow passes through the diverters. As a result, the grease particlesimpact the diverter walls. The collection point is the valley or trough,which both prevents re-entrainment of the grease into the air stream andalso acts as a grease channel to remove grease from the oven cookcavity. This aerodynamic method of grease removal relies on the pressuredrop associated with the turning of the flow through the baffles. Thisdesign achieves approximately 90% removal efficiency of 3 micrometer orgreater grease particles, while requiring less than approximately 1.5inches of water column gas flow pressure drop across the grease particleremoval sections 113 a and 113 b. The flow area restriction is designedto accelerate the gas flow prior to the flow diverters and to slow thegas flow after said flow exits the valleys of the trough.

The most efficient utilization of the spent hot gas is by re-circulationof the gas flow through the oven cavity many times during a cookingcycle. During normal speed cooking it may be desirable for one foodproduct to be cooked after another different type of food product (fishfollowed by pastry) with successive cycles continuing. For exampleshrimp may be cooked first, followed by a baked product or pastry.Without appropriate filtration, the odors from the shrimp willcontaminate the baked product, producing an undesirable taste and odorin the pastry. There exists a need for further air clean-up (in additionto the grease extractors) to further scrub the gas flow of the particlesthat are not entrained by grease extractors 113 a and 113 b. Ininstances wherein further filtration of the gas flow is desired, odorfilters may be placed within the oven cavity. FIG. 12 illustrates theuse of odor filters 140 a and 140 b for this purpose. Left side odorfilter 140 a is attached within top left gas transfer section 117 a,downstream of left grease extractor 113 a and right odor filter 140 b isattached within right gas transfer section 117 b downstream of rightgrease extractor 113 b. Odor filters 140 a and 140 b are attached in amanner that allows for their easy removal for cleaning and replacement.Gas that flows into the left and right gas transfer systems 115 a and115 b first passes through odor filters 140 a and 140 b. The gas flow istherefore further scrubbed after passage through grease extractors 113 aand 13 b in order to eliminate odors that could interfere with theproper taste of the food product currently being cooked. In some casesit may be beneficial to utilize a second set of odor filters, and thesefilters may be placed anywhere within the gas flow path of blower wheels116 a and 116 b. Odor filers 140 a, 140 b may be catalytic type elementsor other filtration means including, but not limited to activatedcharcoal, zeolite or ultra violet wavelight light. It is beneficial thatthe odor filters be comprised of a material, or materials, thateffectively scrubs, or cleans the gas flow with a minimal amount ofinterference with the gas flow velocities. Additionally, it isbeneficial that the odor filters be easily removed, easily cleaned andinexpensive for the operator to replace.

The oven of the present invention may also utilize microwave energy toat least partially cook the food product. As seen in FIG. 11, left sidemicrowave launching waveguide 120 a is attached within oven cavity 102to left side wall 105 between top left gas transfer section 117 a andlower left gas transfer section 118 a. Right side microwave launchingwaveguide 120 b is attached within oven cavity 102 to right side wall106 between top right gas transfer section 117 b and lower right gastransfer section 118 b. The microwave waveguides are designed todistribute microwave power uniformly from the back to the front of ovencook cavity 102. As shown in FIG. 8, such a configuration promotesuniform illumination of microwave energy to the right side and to theleft side of the cook chamber because the microwave energy from the sidewalls is additive over the product. The vertical distance above cavitybottom wall 104 of waveguides 120 a and 120 b is such that, under normalcooking conditions, approximately more than ⅓% of the microwave energyis available below cooking rack 108 a, with the balance of microwaveenergy available above cooking rack 108 a.

Metal cooking devices such as cooking pans, cookie sheets and othermetal cookware is traditionally used in conventional cooking. Becausemicrowave energy cannot penetrate these metal devices, all of themicrowave energy must enter the top and side surfaces of the foodproduct. To overcome the issue that metal pans create, some ovensutilize a top launch microwave system. The theory has been to providemicrowave energy through the top surface of the food product, but thisapplication of microwave power applies excessive microwave energy to thetop of the product, causing over cooking, producing a tough, rubberyfood product. The overcooking problem is especially acute when cookingproteins, such as meat. In order to prevent this microwave overcookcondition, one method historically utilized was a reduction of themicrowave energy that is available for cooking the food product. Theresult of limiting the microwave energy to the food product is that themicrowave energy is more evenly distributed over the cook cavity, butthis reduction in applied microwave energy results in a slower cookprocess, defeating the desire for a speed cooking oven.

Other methods of distributing microwave energy launch microwave energyfrom below the food product. This is not optimum because microwaveenergy that is to enter the upper surface of the food product mustbounce around within the oven cavity in a random and inefficient mannerin order to enter the top side of the food. As shown in FIG, 10 and FIG.11, microwave energy is broadcast from waveguide 120 a into oven cavity102 via a slotted antenna 170 wherein five apertures (slots) 170 a, 170b, 170 c, 170 d and 170 e are spaced along the waveguide. Variousconfigurations for microwave distribution have been utilized withvarying results and the invention is not limited to a microwave launcherwith five slots. Indeed, the number of slots will be determined by thetype of electromagnetic patterns that is desired. Food product 110 isplaced within oven cavity 102 a distance of at least 2.4 inches (foroptimal cooking uniformity) from left side wall 105 or the same distancefrom right side wall 106. The 2.45 inch measurement corresponds to onehalf a microwave wavelength or 2.4 inches (for optimal cookinguniformity) (E field null) for a 2.45 GHz microwave tube (microwave)frequency. This spacing permits the E-field 151 a and 151 b FIG. 7, toexpand and become more uniform prior to coupling with the food product.

The right side microwave system is identical to the left side system andmicrowave energy is broadcast from right waveguide 120 b to oven cavity102 via a slotted antenna as previously described for the left side. Themicrowave energy field therefore propagates through the oven cavity inan evenly distributed pattern, coupling with the food product from alldirections, and providing an even electromagnetic energy distributionthroughout the oven cavity without the need for a mechanical stirrer topropagate the electromagnetic field. Waveguides 120 a and 120 b arelocated on the left and right side walls of the oven, and therefore donot interfere with oven cavity spent gas exhaust and because themicrowave waveguides are located on the side walls of the oven cavity,they are not affected by food spills, grease contamination, cleaningfluid contamination or other contamination that normally affect a bottomlaunch microwave system. The microwave system of the present inventionwill therefore be less likely to be penetrated by grease, spills,cleaning materials and other contaminants because the systems are notlocated directly under the food product where hot contaminants willdrip.

As seen in FIG. 11, bottom wall 4 has a smooth, continuous bottom thatis easy to clean with no heating elements, air return ducts or microwavelaunchers within the oven cavity floor. In those instances where airreturn means, heating elements or microwave launchers protrude throughthe oven floor, it is very difficult for an operator to clean andmaintain the oven in a sanitary condition. In a bottom launch microwavesystem, the waveguide launcher is generally located within the centerportion of the oven cavity bottom wall. As grease, oils and otherby-products of the cooking process are released during normal cooking,they drip and splatter onto the microwave launcher. The launcher must beprotected and is covered with a microwave transparent material such asquartz and sealed with adhesives or other sealants in an effort toprevent contaminants from entering the launcher, causing pre-maturebreakdown of the magnetron. Additionally, some speed cook ovens havelocated upon the bottom wall a radiant element to assist with bottomside browning. For commercial applications an exposed lower radiantelement may result in safety issues as grease builds up around the hotelement.

The gas flow control version also utilizes a smooth oven cavity floorthat does not allow for the contamination of the microwave system, thegas re-circulating system by grease and other by products of the cookingprocess that drip or spill from the cooking containers. Gas dischargeplates 123 a and 123 b, FIG. 11, are located in the corners of the ovenwith the apertures 129 a, 129 b located above the oven floor. Themicrowave launching system is affixed between gas transfer sections 117a and 117 b on the left side and 118 a and 18 b on the right side. Assuch, the bottom of the oven cavity is a continuous, unencumberedsurface. Apertures 129 a and 129 b are positioned above oven bottom wall104 and cleaning of the oven floor is therefore easily achieved.Additionally, plates 127 a and 127 b can be manufactured to be removablefrom lower gas transfer sections 118 a and 118 b for cleaning orreplacement. Radiant elements 103 a and 103 b, are located within gastransfer sections 118 a, and 118 b and will therefore not becontaminated by food spills, grease and cooking by-products thatsplatter and drop from the cooking rack.

Third Version

Another version of the speed cook oven is shown as a multi rack, standalone commercial cooking appliance, but it is obvious to those skilledin the cooking art that this stand alone speed cooking appliance mayexist in many other commercial and residential embodiments (e.g.counter-top oven, wall-oven, single rack oven) because the speed cookoven is scalable up or scalable down. As used herein, the term scalablehas the meaning that additional larger or smaller embodiments can bedeveloped for commercial and residential applications. Of course eachembodiment may have different size characteristics and require differentvoltages of electricity—as commercial power supplies are generallydifferent than residential power supplies. This speed cook oven istherefore not limited to commercial uses only, and is equally applicablefor residential (home) use. With reference to FIGS. 16-20, a speed cookappliance 201 is schematically shown in the form of a multi rack standalone commercial counter top cooking appliance. As used herein, the term“commercial” includes, but is not limited to, the commercial foodservice industry, restaurants, fast food establishments, quick servicerestaurants, convenience stores (to list a few) and other mass feedingestablishments and the term “residential” refers, generally speaking, toresidential applications (home use), although the term is not limited toresidences only, but refers to non-commercial applications for the speedcooking oven.

Appliance 201 includes an oven cavity 202 generally defined by a topwall 203, a bottom wall 204, left side wall 205 a right side wall 206 aback wall 294 and a front wall 295. Oven cavity 202 also has associatedtherewith an access opening 207, FIG. 18, through which food items 210may be placed within oven cavity 102 upon cooking racks 208 a, 208 b,FIG. 16. Although the multi rack embodiment is shown as a countertopoven with two racks 208 a, 208 b, supported by side walls 205 and 206,it is obvious to one skilled in the art that the oven may be made withonly one rack or made with two racks or more than two racks, and withany number of gas delivery systems, and microwave systems, and is notlimited to the two rack design illustrated herein. Although the cookingracks 208 a, 208 b are shown as supported by side walls 205 and 206, itis obvious to one skilled in the cooking art that rack 208 a may be afree-standing cooking rack not supported by the side walls. Cookingappliance 201 has a hinged door 209 FIG. 18 pivotally attached to theoven front for closing the cooking section opening 207 during cookingoperation. Hinged door 209 may be swung between an open position whereinthe door allows access to oven cavity 202 and a closed position whereinthe door covers the opening into oven cavity 202. Although illustratedas a hinged door pivotally attached at the left side of the front of theoven, the door may be hinged on the right side, bottom side or top side.

The speed cooking oven is comprised of two independent gas transfersystems, described herein as a left gas transfer system and a right gastransfer system, wherein left gas transfer system delivers gas to andfrom the left side of the oven cavity 202, and right gas transfer systemdelivers gas to and from the right side of the oven cavity 202. Ovencavity 202 also has associated therewith vent tube 271, FIG. 18, whichallows for the passage of vent gas from oven cavity 202 to atmosphere.Removably affixed within vent tube 271 is odor filter 272, whichprovides for the removal of odors caused by the cooking process. Variousmaterials may be utilized to accomplish odor removal and varyingefficiencies of said materials may be employed. For example, in someinstances it may be desirable for the odor filter to completely (as muchas is possible) filter all odors while at other times it may bedesirable to provide for a less efficient odor filter 272 in order toallow for the passage of some cooking odors. It has been found thatduring the cooking process, for example baking bread, the operator hasan expectation of smelling bread cooking and it may not be desirable tocompletely filter all odors.

Referring to FIG. 16, gas is transferred to and from oven cavity 202 viaa left gas transfer system, which is comprised of a left gas transfersection 215 a, which extends from the front to back of oven top wall203, along the left side of top wall 203. In fluid connection with leftgas transfer section 215 a is top gas egress opening 212, which is opento, and in fluid connection with oven cavity 202 through top wall 203.Top gas egress opening 212 is substantially rectangular, although othergeometries may be employed, and is centrally located within oven topwall 203 and provides for the passage of gas from oven cavity 202 intoleft gas transfer section 215 a, as gases are removed from oven cavity202 through top egress gas egress opening 212. Located within left gastransfer section 215 a is left grease extractor 213 a. As gas is drawnthrough top gas egress opening 212, the gas passes across left heatingmeans 214 a, prior to entry in and through left grease extractor 213 a.Heating means 214 a may include direct fired thermal energy, indirectfired thermal energy, propane, natural gas, electric resistance heatingelements, and other thermal means; and applicant intends to encompasswithin the language any structure presently existing or developed in thefuture that performs the same function. After the gas is drawn acrossheating means 214 a and through left grease extractor 213 a, it is thendrawn through left odor filter 240 a and into left gas transfer section215 a. Alternate locations for left odor filter 240 a can be utilizedwithin the gas flow path and the location of the left odor filteradjacent to left grease extractor 213 a is not required. In fluidconnection with, and located within left gas transfer section 215 a is aleft gas accelerator, illustrated as left blower wheel 216 a. Otherdevices may be utilized to accelerate the gas flow such as a compressor,and applicant intends to encompass within the language any structurepresently existing or developed in the future that performs the samefunction as 216 a, 290 a, 291 a and 216 b, 290 b and 291 b to bediscussed further herein. Connected to left blower wheel 216 a is blowermotor shaft 290 a, which is direct drive with electric motor 291 a.Other means may be employed for coupling blower wheel 216 a to electricmotor 291 a, such as belt drive and the means is not limited to directdrive. Blower wheel 216 a takes gas from oven cavity 202 and deliversthe gas via gas transfer section 217 a to the left top side of ovencavity 202. Top left gas transfer section 217 a, FIG. 18, is in fluidconnection with a center left gas transfer section 243 a via a leftvertical gas transfer section 242 a. Left top vertical transfer section242 a is bounded by left side wall 205 and a top left microwavewaveguide section 246 a. As can be seen in FIG. 16, as gas is pumpedinto top left gas transfer section 217 a, the gas is discharged througha top left discharge plate 223 a into oven cavity 202 via apertures 200a and onto the left top and side portion of food product 210 on top rack208 b. Apertures 200 a may be slotted, regularly formed or irregularlyformed apertures, and are illustrated herein as nozzles 200 a, 270 a,280 a and 229 a, and applicant intends to encompass within the languageany structure presently existing or developed in the future thatperforms the same function as 200 a, 229 a, 270 a 280 a and 200 b and229 b, 270 b, and 280 b, discussed further herein. Gas that has not beendischarged through top left gas discharge plate 223 a flows to centerleft gas transfer section 243 a via vertical transfer section 242 awhere it may be delivered to the lower portion of the food product 210 blocated upon top cooking rack 208 b via apertures 270 a and alsodelivered to the upper surface of a food product 210 a located uponcooking rack 208 a via apertures 280 a. Remaining gas that has not beendelivered through upper gas delivery section 217 a or the centerdelivery section 243 a flows to a lower left gas transfer section 218 avia gas section 242 c, FIG. 16, and may be re-heated, if desired, by alower left heating means 203 a, shown in FIG. 16 before said gas passesthrough slotted or perforated lower left gas discharge plate 227 a viaapertures 229 a, for discharge onto the left bottom and left bottom sideportions of food product 210 a upon lower cooking rack 208 a. Lower leftheating means 203 a may be present in some embodiments and not presentin others depending upon the particular requirements for the speed cookoven. Apertures 200 a, 270 a, 280 a and 229 a are sized for a lowpressure drop, while providing and maintaining sufficient gas velocitiesin the range of approximately 2000 ft/minute to approximately 6000ft/minute properly cook the food product as described herein althoughvelocities above 6000 ft/minute or below 2000 ft/minute may also beutilized if required. As shown in FIG. 16, apertures 200 a and 280 a aresized such that the majority of the gas is supplied from the top leftgas discharge plate 223 a and the downward directed portion of centerdischarge plate 290 a. The resulting imbalance of gas flows between thetop left gas discharge plate 223 a and center discharge plate 290 a ascompared to the upward directed discharge plate 227 a and the upwarddirected portion of discharge plate 290 a is desirable because the topflows to food products 210 a and 210 b must aggressively remove moistureproduced and escaping from the top and top side surface of the foodproducts 210 a and 210 b. The imbalance also serves to heat, brownand/or heat and brown the food products 210 a and 210 b.

Referring again to FIG. 18, gas is transferred to and from oven cavity202 via a right gas transfer system, which is comprised of a right gastransfer section 215 b, which extends from the front to back of oven topwall 203, along the right side of top wall 203. In fluid connection withright gas transfer section 215 b is top gas egress opening 212, which isopen to, and in fluid connection with oven cavity 202 through top wall203. Top gas egress opening 212 is substantially rectangular, althoughother geometries may be employed, and is centrally located within oventop wall 203 and provides for the passage of gas from oven cavity 202into right gas transfer section 215 b, as gases are removed from ovencavity 202 through top egress gas egress opening 212. Located withinright gas transfer section 215 b is right grease extractor 213 b. As gasis drawn through top gas egress opening 212, the gas passes across rightheating means 214 b, prior to entry in and through right greaseextractor 213 b. Heating means 214 b may include direct fired thermalenergy, indirect fired thermal energy, propane, natural gas, electricresistance heating elements, and other thermal means; and applicantintends to encompass within the language any structure presentlyexisting or developed in the future that performs the same function.After the gas is drawn across heating means 214 b and through rightgrease extractor 213 b, it is then drawn through right odor filter 240 band into right gas transfer section 215 b. Alternate locations for rightodor filter 240 b can be utilized within the gas flow path and thelocation of the right odor filter adjacent to right grease extractor 213b is not required. In fluid connection with, and located within rightgas transfer section 215 b is a right gas accelerator, illustrated asright blower wheel 216 b. Other devices may be utilized to acceleratethe gas flow such as a compressor, and applicant intends to encompasswithin the language any structure presently existing or developed in thefuture that performs the same function as 216 b, 290 b, 291 b and 216 b.Connected to right blower wheel 216 b is blower motor shaft 290 b, whichis direct drive with electric motor 291 b. Other means may be employedfor coupling blower wheel 216 b to electric motor 291 b, such as beltdrive and the means is not limited to direct drive. Blower wheel 216 btakes gas from oven cavity 202 and delivers the gas via gas transfersection 217 b to the right top side of oven cavity 202. Top right gastransfer section 217 b, FIG. 16, is in fluid connection with a centerright gas transfer section 243 b via a right vertical gas transfersection 242 b. Right top vertical transfer section 242 b is bounded byright side wall 205 and a top right microwave waveguide section 246 b.As can be seen in FIG. 16, as gas is pumped into top right gas transfersection 217 b, the gas is discharged through a top right discharge plate223 b into oven cavity 202 via apertures 200 b and onto the right topand side portion of food product 210 b on top rack 208 b. Apertures 200b may be slotted, regularly formed or irregularly formed apertures, andare illustrated herein as nozzles 200 b, 270 b, 280 b and 229 b, andapplicant intends to encompass within the language any structurepresently existing or developed in the future that performs the samefunction as 200 b, 229 b, 270 b 280 b. Gas that has not been dischargedthrough top right gas discharge plate 223 b flows to center right gastransfer section 243 b via vertical transfer section 242 b where it maybe delivered to the lower portion of the food product 210 b located upontop cooking rack 208 b via apertures 270 b and also delivered to theupper surface of a food product 210 a located upon cooking rack 208 avia apertures 280 b. Remaining gas that has not been delivered throughupper gas delivery section 217 b or the center delivery section 243 bflows to a lower right gas transfer section 218 b via gas section 242 d,FIG. 16, and may be re-heated, if desired, by a lower right heatingmeans 203 b, shown in FIG. 16 before said gas passes through slotted orperforated lower right gas discharge plate 227 b via apertures 229 b,for discharge onto the right bottom and right bottom side portions offood product 210 a upon lower cooking rack 208 a. Lower right heatingmeans 203 b may be present in some embodiments and not present in othersdepending upon the particular requirements for the speed cook oven.Apertures 200 b, 270 b, 280 b and 229 b are sized for a low pressuredrop, while providing and maintaining sufficient gas velocities in therange of approximately 2000 ft/minute to approximately 6000 ft/minuteproperly cook the food product as described herein although velocitiesabove 6000 ft/minute or below 2000 ft/minute may also be utilized ifrequired. As shown in FIG. 16, apertures 200 b and 280 b are sized suchthat the majority of the gas is supplied from the top right gasdischarge plate 223 b and the downward directed portion of centerdischarge plate 290 b. The resulting imbalance of gas flows between thetop right gas discharge plate 223 b and center discharge plate 290 b ascompared to the upward directed discharge plate 227 b and the upwarddirected portion of discharge plate 290 b is desirable because the topflows to food products 210 a and 210 b must aggressively remove moistureproduced and escaping from the top and top side surface of the foodproducts 210 a and 210 b. The imbalance also serves to heat, brownand/or heat and brown the food products 210 a and 210 b.

The left and right gas supply systems, although independently describedherein, are the same configuration and function to uniformly circulatehot gas flow across the top and top sides and bottom and bottom sides ofthe food product, and return the gas to the heating mechanism forre-delivery to the cooking cavity.

As described, the gas flow is delivered via the six gas transfersections 217 a, 217 b, 243 a, 243 b, 218 a, and 218 b, wherein sections217 a, 217 b, 218 a and 218 b are located in the top and bottom comersof oven cavity 202 and sections 243 a and 243 b are located betweenwaveguides 246 a and 220 a and 246 b and 220 b respectively. Gas flowtransfer sections 217 a, 217 b, 243 a, 243 b, 218 a and 218 b extendfrom the back wall 294 of the oven cavity to the front wall 295 of theoven cavity, although it is not required that the gas flow transfersections extend the entire depth of the oven cavity. Gas transfersection 217 a is located in the top left corner of oven cavity 202 wheretop wall 203 intersects oven cavity side wall 205; gas transfer section217 b in the top right corner of oven cavity 202 where top wall 203intersects right side wall 206; gas transfer section 218 a in the lowerleft corner of oven cavity 202 where bottom wall 204 intersects leftside wall 205; and gas transfer section 218 b in located the lower rightcorner of the oven cavity where bottom wall 204 intersects right sidewall 206. Gas transfer sections 243 a is located between waveguides 246a and 220 a and gas transfer section 243 b is located between waveguidesections 246 b and 220 b. The gas transfer sections extend along theinside of oven cavity 202 from the back wall 294 of the oven cavity tothe front wall 295 of the oven cavity. Each of the gas transfer sectionsare sized and configured to deliver the appropriate gas flow for theparticular oven utilized. For example, in a smaller oven, the gasdelivery sections, indeed the entire oven, may be sized smaller inproportion to the smaller footprint of the particular requirements, anda larger oven will have proportionally larger gas delivery sections. Asseen in FIG. 16, the left side and the right side gas flows converge onthe food products 210 a and 210 b thereby creating an aggressive flowfield on the food product surface that strips away the moisture boundarylayer. This turbulently mixed gas flow directed at the food product canbest be described as glancing, conflicting and colliding gas flowpatterns that spatially average the gas flow over the surface area ofthe food product producing high heat transfer and moisture removal ratesat the food surface, thereby optimizing speed cooking. The gas flow isdirected towards the top, the bottom and the sides of the food productfrom the left and right sides of the oven cavity and the left and rightside gas flows conflict, collide and glance off each other at the foodproduct surface before exiting the oven cavity through top gas egressopening. As used herein, the terms “mix”, “mixing”, “turbulent mix” and“turbulent mixing”. The gas flow is directed towards the top, the bottomand the sides of the food product from the left and right sides of theoven cavity and the left and right side gas flows conflict, collide andglance off each other at the food product surface before exiting theoven cavity through top gas egress opening 212. The oven of the presentinvention does not require smooth gas flow, laminar gas flow or air wrapgas flow. The glancing, conflicting and colliding gas flows patterns arecreated within the oven cavity and, when appropriately directed anddeflected, produces a high quality cooked food product very quickly.Enhancing the highly agitated, glancing, conflicting, and colliding gasflow of the present invention is the general upward flow path the gaswill follow, as shown in FIG. 16, through top gas egress opening 212, asthe gas exits the top of oven cavity 202. This upward gas flow drawsalso the gas from lower gas discharge sections 218 a and 218 b andcenter gas discharge sections 243 a and 243 b, thereby scrubbing thebottom of the food product, pot, pan or other cooking vessel, around thesides of said vessel and further enhances the heat transfer as well asdrawing the gas that scrubs the upper surface up towards the oven cavitytop wall.

Returning to FIG. 16, top gas discharge plates 223 a and 223 b arepositioned within oven cavity 202 such that the gas flow from top gastransfer section 217 a mixes with the gas flow from top gas transfersection 217 b upon the top and top side surfaces of food product 210 band strikes the food product at an angle that is between zero degreesand ninety degrees as referenced from the horizontal top wall (wherezero degrees is parallel to the horizontal top wall).

Lower gas discharge plates 227 a and 227 b are positioned within ovencavity 202 such that the gas flow from lower gas transfer section 218 amixes with the gas flow from lower gas transfer section 218 b upon thelower and lower side surface of food product 210 a and strikes the foodproduct at an angle that is between zero degrees and ninety degrees asreferenced from the horizontal top wall.

Center gas discharge plates 295 a and 295 b are positioned within ovencavity 202 such that the gas flow from the upward pointing section ofgas discharge plate 295 a mixes with the gas flow from the upwardpointing section of gas discharge plate 295 b upon the lower surface andlower side surface of food product 210 b upon upper cooking rack 208 band strikes the food product at an angle that is between zero degreesand ninety degrees as referenced from the horizontal bottom wall,although, just as with the top and bottom gas delivery sections, centerdelivery sections 295 a and 295 b can be set at an angle that can beadjusted from zero degrees to ninety degrees as referenced from thehorizontal bottom wall. The downward pointing section of gas dischargeplate 295 a mixes with the gas flow from the downward pointing sectionof gas discharge plate 295 b upon the upper surface and upper sidesurface of food product 210 a upon lower cooking rack 208 a and strikesthe food product at an angle that is between zero degrees and ninetydegrees as referenced from the horizontal bottom wall, although, just aswith the top and bottom gas delivery sections, center delivery sections295 a and 295 b can be set at an angle that can be set fromapproximately zero degrees to approximately degrees from the horizontalbottom wall and adjustments may be made either at the site ofmanufacture or, alternatively in some instances, adjusted by the user asdesired. As described herein, all gas delivery section for all versionsor embodiments may be made adjustable and applicant intends to encompasswithin the language any structure presently existing or developed in thefuture that performs the same function as adjustment to the angles ofgas delivery sections and gas delivery plates.

The number and placement of the apertures 200 a, 200 b, 270 a, 270 b 229a and 200 b, and 280 a and 280 b will vary according to the particularoven that is required. As described herein, this invention is “scalable”and as used herein the term scalable has the meaning that the technologywill provide for a platform of products, not merely one particular sizeor one particular product. If, for example, a speed cooking baking ovenwere desired (as opposed to a general purpose speed cooking oven whichcooks proteins, baked products, etc.) the apertures may be larger, butfewer in number. This would allow for a more gentle gas flow fieldacross the food product, and therefore more delicate baking of the foodproduct. If a browning oven were desired, the apertures may be morenumerous and smaller in diameter. Additionally, the operator may desireflexibility of cooking and in this circumstance, gas discharge plates223 a, 223 b, 295 a, 295 b and 227 a and 227 b may be fabricated in amanner that allows for change-out of the plates. As used herein the term“aperture” refers to irregular slots, holes or nozzles, regularly formedslots, irregularly formed holes or nozzles or a mixture of regularlyformed and irregularly formed slots, holes or nozzles.

The gas delivery system as illustrated in FIG. 16, as described herein,produces aggressive glancing, conflicting and conflicting gas flowpatterns 330 a and 330 b, FIG. 16, wherein gas flow is directed onto thetop surfaces of the food products 210 a and 210 b. An aggressive topglancing, conflicting and colliding gas flow pattern 330 a is directedtowards the left top of food product 210 a and 210 b and also interactswith the left top portion and left top side portion of food products 210a and 210 b. A similar right top glancing, conflicting and colliding gasflow pattern 330 b interacts with the top portion and top right sideportion of food products 210 a and 210 b.

As seen in FIG. 16, gas flow is also directed upwardly from the centergas transfer sections 243 a and 243 b and the lower gas transfersections 218 a and 218 b. As such, aggressive glancing, conflicting andcolliding gas flow patterns 331 a and 331 b interact with the lower leftand right portions of the food products 210 a and 210 b. This cookingprofile creates high heat transfer capability by using the irregularsurface of the food product, as well as the interference of flow fieldsto minimize boundary layer growth. The angle of the gas flow velocityvector leaving the top left and top right discharge plates 223 a and 223b respectively, the center discharge plates 295 a and 295 b (both upwardand downward gas flow), and the gas flow from the bottom left and bottomright discharge plates 227 a and 227 b respectively, is between zerodegrees and ninety degrees from horizontal bottom wall 204. After theaggressive glancing conflicting and conflicting gas flow patterns 330 aand 330 b, 331 a and 331 b contact or strike the food product they areexhausted through top egress section 212 and cycle back through the ovenas described herein.

The gas flows within the multi rack oven, as well as other functions ofcooking appliance are directed by controller 234, FIG. 1. Controller 234determines, among other things, the velocity of gas flow, which may beconstant or varied, or, may be constantly changed throughout the cookingcycle. It may be desired to cook the food product on one velocitythroughout the entire cooking cycle, or to vary the gas velocitydepending upon conditions such as a pre-determined cooking algorithm, orvary the velocity in response to various sensors that may be placedwithin the oven cavity, oven return air paths or various other positionswithin the oven. The location and placement of said sensors will bedetermined by the particular application of the oven. Additionally,other means may be utilized wherein data is transmitted back tocontroller 234, and thereafter controller 234 adjusts the cooking in anappropriate manner. For example sensors (temperature, humidity,velocity, vision and airborne chemical mixture level sensors) may beutilized to constantly monitor the cooking conditions and adjust the gasflow accordingly within a cooking cycle, and other sensors not describedherein may also be utilized. The speed cooking oven may utilize sensorsthat are not currently commercially utilized (such as laser,non-invasive temperature sensors and other sensors that are currentlytoo expensive to be commercially feasible), and the speed cooking ovenis not limited to those discussed herein, as many sensing devices areknown and utilized in the cooking art.

The gas flow performance may also be adjusted as a function of availablepower. In the event, for example, the heating system in an all electricspeed cooking oven is requiring or utilizing a large amount of power(larger than available power levels which may vary according to locationand local code and ordinance) it may be desirable for the controller toreduce electrical power to the convection heaters or other electricalcomponents accordingly in order to conserve available power. Indeed, incertain parts of the world where power is limited or capped, for exampleJapan and Italy, the oven of the present invention can be designed toadjust to these limiting conditions. In a speed cooking gas fired unit,some systems will be powered by electric current, but the electric powerrequirements will not be as high as required for an all electric ovenbecause the energy required for gas heating and cooking will be providedby the combustion of a hydrocarbon based fuel. In this event acontroller may not be required, indeed knobs or dials may be utilized.

Managing the gas flow pattern in a speed cooking oven is importantrelative to controlling the local convection heat transfer rate at thefood product. Many food products cooked in a typical rapid cook ovenrequire that the energy into the food (whether the energy be microwave,impingement gas, halogen light or other energy) be “tailored”(distributed) over the entire cooking cycle. This tailoring ormodulation of both the microwave and the convection energy systems is animportant feature in achieving a rapidly cooked food product with highfood quality. For example, a food product such as a pizza may require asmuch as 30 minutes to cook in a conventional oven, but can be cooked inas little as 3 minutes in a speed cooking oven. During this three minutecooking cycle, the controller may be programmed with an overall routineof cooking instructions that is broken down into sub-routines or events.As such, in a cooking profile, several different “sub-routines” may beutilized to attain the final rapidly cooked food product. The cook cyclemay, for example begin with 20 seconds of high velocity gas flow whereinthe gas flow is delivered at 100% velocity and the microwave output is10% of total microwave capacity. This cycle may then, for example, befollowed with 10 seconds of cooking time wherein 10% gas flow isutilized and no microwave power is used. This may then be followed by 1minute wherein 100% gas flow and 100% microwave power is used, followedby, for example, one minute wherein 50% microwave power is used and 50%gas flow is utilized. These speed cooking ovens therefore require asophisticated control mechanism that is expensive and can be a source ofreliability problems and variable speed blowers have therefore been usedin order to control, for example, vertical impingement air flow and aspreviously described, this approach is expensive because dynamicallybraking speed variable blower motor speed controllers are required,adding complexity and cost to the appliance. In addition, using air flowrates that vary from low flows to high flows requires “over-design” ofoven components such as convection heaters, grease control systems,blowers, blower motor controllers and nozzle plates because the partsmust work equally well together at low flow conditions as well as athigh flow conditions.

Although the present invention may utilize variable speed blower motorsand variable speed blower motor controllers, there is no requirement fortheir use and the speed cooking oven of the present invention avoidsthese problems, and the complexity of the variable speed blower motors,by maintaining a substantially constant gas glow rate through the ovencavity, gas transfer and gas delivery sections. One means to achievethis gas flow pattern modification is by use of a gas pumping means, inthis illustration, a blower motor, blower wheel combination, utilizing acontroller or a multi speed switch that allows for the switching of theblower motor speed in pre-determined fixed increments. Heating of theconvection gas is provided by either electric resistance heating means214 a and 214 b or by a direct fired (product of combustion mix withoven gas) means. The heater is configured such that it can be operatedat a lower heat flux for the convection heating and cooking mode, or ata higher rate for radiant heating and cooking. The radiant heating willalso provide convection heat for cooking. The purpose of the radiantfeature is to provide additional surface browning.

The speed cooking process produces a high grease generation rate becausethe amount of grease or liquids that are produced during a rapid cookoperation is approximately the same as conventional cooking, but thegrease load is produced in ⅕^(th) to 1/7^(th) and in some instances1/10^(th) the time of conventional cooking times. This results in highgrease loading (e.g. ounces/minute) of the gas flow stream which, if nottreated, may cause a number of problems including (a) smoke generation,as grease particles impact hot surfaces, (b) soiling of interior gastransfer and delivery surfaces, which may be hidden and difficult toclean, and (c) grease contamination of the food product itself from there-circulated air flow. Impingement style air flow amplifies this effectby throwing or entraining grease and other liquids that ultimatelycollect in the grease catch container around the food product. The gasflow of the present invention greatly reduces this effect by notallowing the gas flow to impinge on the liquid coated pan, cookingvessel or food surfaces. In order to control the grease and otherliquids produced by the speed cooking process, the first method employedis the particle removal of the grease. Grease in vapor form is much lessof an issue because there are no cool walls within the oven for vaporcondensation of the grease or liquid. Referring now to FIG. 16 and FIG.18, left grease extractor 213 a and right grease extractor 213 b arepositioned downstream of left thermal heating means 214 a and rightthermal means 214 b respectively. The gas flow passes over left andright thermal means 214 a and 214 b before passing through left andright grease extractors 213 a and 213 b. In order to control grease andother liquid particles, grease extractors 213 a and 213 b are designed,FIG. 19 b, to provide a convoluted gas flow path, 280 wherein theaverage flow velocity maintained is in the approximately 2000 ft/minuteto approximately 6000 ft/min range although velocities above 6000ft/minute may be utilized and velocities below 2000 ft/minute may alsobe used. This method will extract a substantial amount of the greaseparticles with mean diameters greater than approximately 3.0micrometers. Grease extractors 213 a and 213 b have a proximal endtowards the front of oven cavity 202 and a distal end towards the backwall of oven cavity 202 wherein the distal end is positioned slightlylower than the proximal end to allow grease to flow by means of gravityto the back wall of oven cavity 202 where it is collected within agrease collection means 250, FIG. 19 a, or otherwise removed completelyfrom the oven via a tube, channel or other means that allows the liquidgrease to collect in a collection device separate and apart from thespeed cooking oven. Grease extractors 213 a and 13 b consist of a seriesof baffles or troughs 281 that rapidly accelerates (change of direction)the flow 280 as the gas flow bends around the flow diverters. Larger orheavier grease particles with the highest inertia cannot be sufficientlyaccelerated to follow the flow as the flow passes through the diverters.As a result, the grease particles impact the diverter walls. Thecollection point is the valley or trough, which both preventsre-entrainment of the grease into the air stream and also acts as agrease channel to remove grease from the oven cook cavity. Thisaerodynamic method of grease removal relies on the pressure dropassociated with the turning of the flow through the baffles. This designachieves approximately 90% removal efficiency of 3 micrometer or greatergrease particles, while requiring less than approximately 1.5 inches ofwater column gas flow pressure drop across the grease particle removalsections 213 a and 213 b. The flow area restriction is designed toaccelerate the gas flow prior to the flow diverters and to slow the gasflow after said flow exits the valleys of the trough.

The most efficient utilization of the spent hot gas is by re-circulationof the gas flow through the oven cavity many times during a cookingcycle. During normal speed cooking it may be desirable for one foodproduct to be cooked after another different type of food product (fishfollowed by pastry) with successive cycles continuing. For exampleshrimp may be cooked first, followed by a baked product or pastry.Without appropriate filtration, the odors from the shrimp willcontaminate the baked product, producing an undesirable taste and odorin the pastry. There exists a need for further air clean-up (in additionto the grease extractors) to further scrub the gas flow of the particlesthat are not entrained by grease extractors 213 a and 213 b. Ininstances wherein further filtration of the gas flow is desired, odorfilters may be placed within the oven cavity. FIG. 16 illustrates theuse of odor filters 240 a and 240 b for this purpose. Left side odorfilter 240 a is attached within top left gas transfer section 217 a,downstream of left grease extractor 213 a and right odor filter 240 b isattached within right gas transfer section 217 b downstream of rightgrease extractor 213 b. Odor filters 240 a and 240 b are attached in amanner that allows for their easy removal for cleaning and replacement.Gas that flows into the left and right gas transfer systems 215 a and215 b first passes through odor filters 240 a and 240 b. The gas flow istherefore further scrubbed after passage through grease extractors 213 aand 213 b in order to eliminate odors that could interfere with theproper taste of the food product currently being cooked. In some casesit may be beneficial to utilize a second set of odor filters, and thesefilters may be placed anywhere within the gas flow path. Odor filers 240a and 240 b may be catalytic type elements or other filtration meansincluding, but not limited to activated charcoal, zeolite or ultraviolet wavelight light. It is beneficial that the odor filters becomprised of a material, or materials, that effectively scrubs, orcleans the gas flow with a minimal amount of interference with the gasflow velocities. Additionally, it is beneficial that the odor filters beeasily removed, easily cleaned and inexpensive for the operator toreplace.

The oven of the present invention may also utilize microwave energy toat least partially cook the food product. As seen in FIG. 16, left sidemicrowave launching waveguides 220 a and 242 a are attached within ovencavity 202 to left side wall 205 between top left gas transfer section217 a, center gas section 243 a and lower left gas transfer section 218a. Right side microwave launching waveguides 220 b and 242 b areattached within oven cavity 202 to right side wall 206 between top rightgas transfer section 217 b, center gas section 243 b and lower right gastransfer section 218 b. The microwave waveguides are designed todistribute microwave power uniformly from the back to the front of ovencook cavity 202. Such a configuration promotes uniform illumination ofmicrowave energy to the right side and the left side of the cook chamberbecause the microwave energy from the side walls is additive over theproduct. The vertical distance above cavity bottom wall 204 ofwaveguides 220 a, 220 b, 242 a and 242 b is such that, under normalcooking conditions, approximately more than ⅓% of the microwave energyis available below each cooking racks 208 a and 208 b, with the balanceof microwave energy available above cooking racks 208 a and 208 b.

Metal cooking devices such as cooking pans, cookie sheets and othermetal cookware is traditionally used in conventional cooking. Becausemicrowave energy cannot penetrate these metal devices, all of themicrowave energy must enter the top and side surfaces of the foodproduct. To overcome the issue that metal pans create, some ovensutilize a top launch microwave system. The theory has been to providemicrowave energy through the top surface of the food product, but thisapplication of microwave power applies excessive microwave energy to thetop of the product, causing over cooking, producing a tough, rubberyfood product. The overcooking problem is especially acute when cookingproteins, such as meat. In order to prevent this microwave overcookcondition, one method historically utilized was a reduction of themicrowave energy that is available for cooking the food product. Theresult of limiting the microwave energy to the food product is that themicrowave energy is more evenly distributed over the cook cavity, butthis reduction in applied microwave energy results in a slower cookprocess, defeating the desire for a speed cooking oven.

Other methods of distributing microwave energy launch microwave energyfrom below the food product. This is not optimum because microwaveenergy that is to enter the upper surface of the food product mustbounce around within the oven cavity in a random and inefficient mannerin order to enter the top side of the food. As shown in FIG. 17,microwave energy is broadcast from waveguides 220 a, 220 b, 246 a and246 b into oven cavity 202 via a slotted antenna wherein four narrowapertures (slots) 270 a, 270 b, 270 c, 270 d and 270 e are spaced alonethe waveguide. Various configurations for microwave distribution havebeen utilized with varying results and the design is not required orlimited to the five slots as illustrated. Indeed, fewer slots or moreslots may be utilized depending upon the length of the microwavelauncher and the desired electromagnetic energy field that is required.Food products 210 a and 210 b are placed within oven cavity 202 adistance of at least 2.4 inches (for optimal cooking uniformity) fromleft side wall 205 or right side wall 206. The 2.45 inch measurementcorresponds to one half a microwave wavelength or 2.4 inches (foroptimal cooking uniformity) (E field null) for a 2.45 GHz microwave tube(microwave) frequency. This spacing permits the E-field to expand andbecome more uniform prior to coupling with the food product. The leftand right microwave systems are identical and illustrated in FIG. 16.

The microwave energy field therefore propagates through the oven cavityin an evenly distributed pattern, coupling with the food product fromall directions, and providing an even electromagnetic energydistribution throughout the oven cavity without the need for amechanical stirrer to propagate the electromagnetic field.

Waveguides 220 a, 220 b, 246 a and 246 b are located on the left andright side walls of the oven, and therefore do not interfere with ovencavity spent gas exhaust and are not affected by food spills, greasecontamination, cleaning fluid contamination or other contamination thatnormally affect a bottom launch microwave system. The microwave systemof the present invention will therefore be less likely to be penetratedby grease, spills, cleaning materials and other contaminants because thesystems are not located directly under the food product where hotcontaminants will drip.

As seen in FIG. 16, bottom wall 204 has a smooth, continuous bottom thatis easy to clean with no heating elements, air return ducts or microwavelaunchers within the oven cavity floor. In instances where air returnmeans, heating elements and microwave launchers protrude through theoven floor it is very difficult for an operator to clean and maintainthe oven in a sanitary condition. In a bottom launch microwave system,the waveguide launcher is generally located within the center portion ofthe oven cavity bottom wall. As grease, oils and other by-products ofthe cooking process are released during normal cooking, they drip andsplatter onto the microwave launcher. The launcher must be protected andis covered with a microwave transparent material such as quartz andsealed with adhesives or other sealants in an effort to preventcontaminants from entering the launcher, causing pre-mature breakdown ofthe magnetron. Additionally, some speed cook ovens have located upon thebottom wall a radiant element to assist with bottom side browning. Forcommercial applications an exposed lower radiant element may result insafety issues as grease builds up around the hot element.

The present invention utilizes a smooth oven cavity floor that does notallow for the contamination of the microwave system, the gasre-circulating system or the wave guide launcher by grease and other byproducts of the cooking process that drip or spill from the cookingcontainers. Gas discharge plates 223 a and 223 b, FIG. 16 are located inthe corners of the oven with the apertures 229 a, 229 b located abovethe oven floor. As such, the bottom of the oven cavity is left as acontinuous, unencumbered surface. Apertures 229 a and 229 b arepositioned above oven bottom wall 204 and cleaning of the oven floor istherefore easily achieved. Additionally, plates 227 a and 227 b can bemanufactured to be removable from lower gas transfer sections 218 a and218 b for cleaning or replacement. Radiant elements 203 a and 203 b, arelocated within gas transfer sections 218 a, and 218 b and will thereforenot be contaminated by food spills, grease and cooking by-products thatsplatter and drop from the cooking rack.

To summarize, the present invention provides for a speed cooking ovenutilizing hot gas flows, hot gas flows coupled with microwave energy inorder to achieve speed cooking of food products five to ten times fasterthan conventional cooking methods, and at quality, taste and appearancelevels that are equal to and exceed conventional cooking. In the variousversions, the oven is operable on standard commercial power supplies andis simple and economical to manufacture, use and maintain, and isdirectly scalable to larger or smaller commercial and larger or smallerresidential embodiments. The speed cooking oven may operate as a speedcooking air only oven, a microwave oven or a combination air andmicrowave speed cooking oven.

Although the present invention has been described in considerable detailwith reference to certain preferred versions thereof, other versions arepossible. For example, various sizes of commercial and residential speedcooking ovens may be made. In these cases larger or smaller componentparts may be utilized and fewer or more components may be employed. Inthe case where it is desirable to make a smaller speed cooking oven, onegas flow acceleration means may be utilized instead of two; onemicrowave system utilized instead of two; smaller or fewer thermaldevices, whether electric resistance or gas fired may be used. In caseswherein it is desirable for a larger speed cooking oven, multiple rackunits may be developed and additional gas flow systems and microwavesystems may be added to accomplish a larger cavity, multi rack speedcooking oven. Apertures may be made larger or smaller depending upon thegas flow requirements of a practiced version. The heating means may becombined into one heating element, or more than two heating elements maybe utilized.

Any element in a claim that does not explicitly state “means for”performing a specific function, or “step for” performing a specificfunction, is not to be interpreted as a “means” or “step” clause asspecified in 35 U.S.C. §112, ¶6. In particular, the use of “step” of inthe claims herein is not intended to invoke the provisions of 35 U.S.C.§112,

Other modifications and improvements thereon will become readilyapparent to those skilled in the art. Accordingly, the spirit and scopeof the present invention is to be considered broadly and limited only bythe appended claims, and not by the foregoing specification.

Other modifications and improvements thereon will become readilyapparent to those skilled in the art. Accordingly, the spirit and scopeof the present invention is to be considered broadly and limited only bythe appended claims, and not by the foregoing specification.

1. A speed cooking oven for cooking a food product by hot gas andmicrowave energy, said oven comprising: (a) an oven cavity forcontaining said food product, said oven cavity having a bottom; (b) aconduit means associated with the cooking chamber, said conduit meansproviding for the circulation of the gas to and from the cookingchamber; (c) a variable speed blower motor for causing circulation ofthe gas; (d) a thermal means for heating the gas; (e) a control meansfor controlling the gas; (f) a first gas directing means associated withthe conduit means and disposed above the food product and above saidbottom of the oven cavity; (g) a second gas directing means associatedwith the conduit means disposed above the food product and above saidbottom of the oven cavity, wherein the first and second gas directingmeans are configured to cause the gas from the first gas directing meansto collide with the gas from the second gas directing means upon theupper surface of the food product; (h) a third gas directing meansassociated with the conduit means and disposed below the food productand above said bottom of the oven cavity; (i) a fourth gas directingmeans associated with the conduit means disposed below the food productand above said bottom of the oven cavity, wherein the third and fourthgas directing means are configured to cause the gas from the third gasdirecting means to collide with the gas from the fourth gas directingmeans upon the bottom surface of the food product; (j) microwavewaveguides disposed above said bottom of the oven cavity for launchingmicrowave energy into the oven cavity: (k) wherein said bottom of theoven cavity is smooth and continuous with no heating elements, air ductsor microwave launchers to facilitate easy cleaning of the bottom of theoven cavity.
 2. The speed cooking oven according to claim 1, wherein thegas is circulated at a velocity of about 2000 feet per minute or higher.3. The speed cooking oven according to claim 1, wherein the gas iscirculated at a velocity of about 6000 feet per minute or lower.
 4. Thespeed cooking oven according to claim 1, wherein the gas is circulatedat a velocity in the range between about 2000 feet per minute and 6000feet per minute.
 5. The speed cooking oven according to claim 1, whereinthe gas is circulated at a velocity of up to 2000 feet per minute. 6.The speed cooking oven according to claim 1, wherein the gas iscirculated at a velocity of 6000 feet per minute or higher.
 7. The speedcooking oven according to claim 4 wherein said first and second gasdirecting means direct gas from opposite sides of the oven cavity. 8.The speed cooking oven according to claim 7 wherein said microwavewaveguides launch microwave energy from said opposite sides of the ovencavity.